diff --git a/api/src/model/entitites/cylinder.entity.ts b/api/src/model/entitites/cylinder.entity.ts
index e65d91b..2b8792e 100644
--- a/api/src/model/entitites/cylinder.entity.ts
+++ b/api/src/model/entitites/cylinder.entity.ts
@@ -21,7 +21,7 @@ export class Cylinder {
   @Column({ nullable: false, unique: true })
   name: string;
 
-  @ManyToMany(() => Key, (key) => key.cylinder)
+  @ManyToMany(() => Key, (key) => key.cylinder, { onDelete: 'NO ACTION'})
   keys: Key[];
 
   @ManyToOne(() => KeySystem, (sys) => sys.cylinders)
diff --git a/api/src/model/entitites/index.ts b/api/src/model/entitites/index.ts
index abea36b..28c4a56 100644
--- a/api/src/model/entitites/index.ts
+++ b/api/src/model/entitites/index.ts
@@ -3,7 +3,6 @@ export * from './user.entity';
 export * from './role.entity';
 export * from './cylinder.entity';
 export * from './key.entity';
-export * from './key_activity.entity';
 export * from './customer.entity';
 export * from './key-handout.entity';
 export * from './activity.entity';
diff --git a/api/src/model/entitites/key_activity.entity.ts b/api/src/model/entitites/key_activity.entity.ts
deleted file mode 100644
index 71ace39..0000000
--- a/api/src/model/entitites/key_activity.entity.ts
+++ /dev/null
@@ -1,42 +0,0 @@
-import {
-  Column,
-  CreateDateColumn,
-  Entity,
-  ManyToMany,
-  ManyToOne,
-  PrimaryGeneratedColumn,
-} from 'typeorm';
-import { User } from './user.entity';
-import { IKey } from '../interface/key.interface';
-import { Cylinder } from './cylinder.entity';
-import { Customer } from './customer.entity';
-
-@Entity()
-export class KeyActivity implements IKey {
-  @PrimaryGeneratedColumn()
-  primaryId: number;
-
-  @Column()
-  id: string;
-
-  @Column({ nullable: true })
-  name: string;
-
-  @Column({ name: 'key_number' })
-  nr: string;
-
-  @Column({ name: 'handed_out', default: false })
-  handedOut: boolean;
-
-  @ManyToMany(() => Cylinder)
-  cylinder: Cylinder[];
-
-  @ManyToOne(() => Customer)
-  customer: Customer;
-
-  @CreateDateColumn({ name: 'created_at' })
-  createdAt: Date;
-
-  @ManyToOne(() => User)
-  user: User;
-}
diff --git a/api/src/model/repositories/index.ts b/api/src/model/repositories/index.ts
index d581d63..9629f28 100644
--- a/api/src/model/repositories/index.ts
+++ b/api/src/model/repositories/index.ts
@@ -4,6 +4,5 @@ export * from './role.repository';
 export * from './system.repository';
 export * from './cylinder.repository';
 export * from './key.repository';
-export * from './key_activity.repository';
 export * from './customer.repository';
 export * from './activity.repository';
diff --git a/api/src/model/repositories/key_activity.repository.ts b/api/src/model/repositories/key_activity.repository.ts
deleted file mode 100644
index 1e23e4a..0000000
--- a/api/src/model/repositories/key_activity.repository.ts
+++ /dev/null
@@ -1,10 +0,0 @@
-import { Injectable } from '@nestjs/common';
-import { Repository, DataSource } from 'typeorm';
-import { KeyActivity } from '../entitites';
-
-@Injectable()
-export class KeyActivityRepository extends Repository<KeyActivity> {
-  constructor(dataSource: DataSource) {
-    super(KeyActivity, dataSource.createEntityManager());
-  }
-}
diff --git a/api/src/modules/customer/customer.service.ts b/api/src/modules/customer/customer.service.ts
index 618e2eb..3a69f89 100644
--- a/api/src/modules/customer/customer.service.ts
+++ b/api/src/modules/customer/customer.service.ts
@@ -8,9 +8,16 @@ export class CustomerService {
   constructor(private customerRepository: CustomerRepository) {}
 
   createCustomer(user: IUser, data: any) {
-    if (!user || !data.name || data.name.length == 0 || !data.system) {
-      throw new HttpException('invalid', HttpStatus.UNPROCESSABLE_ENTITY);
+    if (!user) {
+      throw new HttpException({ message: 'Der Benutzer ist nicht verfügbar.', field: 'user' }, HttpStatus.UNPROCESSABLE_ENTITY);
     }
+    if (!data.name || data.name.length === 0) {
+      throw new HttpException({ message: 'Der Name des Kunden ist erforderlich.', field: 'name' }, HttpStatus.UNPROCESSABLE_ENTITY);
+    }
+    if (!data.system) {
+      throw new HttpException({ message: 'Die Schließanlage ist nicht gefüllt.', field: 'system' }, HttpStatus.UNPROCESSABLE_ENTITY);
+    }
+
 
     return this.customerRepository.save(this.customerRepository.create(data));
   }
diff --git a/api/src/modules/cylinder/cylinder.module.ts b/api/src/modules/cylinder/cylinder.module.ts
index 7883dc8..b9eef54 100644
--- a/api/src/modules/cylinder/cylinder.module.ts
+++ b/api/src/modules/cylinder/cylinder.module.ts
@@ -3,10 +3,11 @@ import { CylinderController } from './cylinder.controller';
 import { CylinderService } from './cylinder.service';
 import { AuthModule } from '../auth/auth.module';
 import { DatabaseModule } from 'src/shared/database/database.module';
+import { SharedServiceModule } from 'src/shared/service/shared.service.module';
 
 @Module({
   controllers: [CylinderController],
   providers: [CylinderService],
-  imports: [AuthModule, DatabaseModule],
+  imports: [AuthModule, DatabaseModule, SharedServiceModule],
 })
 export class CylinderModule {}
diff --git a/api/src/modules/cylinder/cylinder.service.ts b/api/src/modules/cylinder/cylinder.service.ts
index 6d13572..398f305 100644
--- a/api/src/modules/cylinder/cylinder.service.ts
+++ b/api/src/modules/cylinder/cylinder.service.ts
@@ -1,6 +1,7 @@
-import { Injectable } from '@nestjs/common';
+import { HttpException, HttpStatus, Injectable } from '@nestjs/common';
 import { Cylinder, User } from 'src/model/entitites';
 import { ActivityRepository, CylinderRepository, KeyRepository } from 'src/model/repositories';
+import { ManageHelperService } from 'src/shared/service/system.helper.service';
 
 @Injectable()
 export class CylinderService {
@@ -8,6 +9,7 @@ export class CylinderService {
     private readonly cylinderRepo: CylinderRepository,
     private readonly keyRepo: KeyRepository,
     private systemActivityRepo: ActivityRepository, 
+    private readonly helper: ManageHelperService
   ) {}
 
   async getCylinders(user: User): Promise<Cylinder[]> {
@@ -16,24 +18,26 @@ export class CylinderService {
       order: { name: { direction: 'ASC' } },
       relations: ['system', 'keys'],
     });
-    c.map((cc) => (cc.keys = []));
     return c;
   }
 
   async deleteCylinder(user: User, cylinderid: string) {
-    const cylinder = await this.cylinderRepo.findOneOrFail({
-      where: { id: cylinderid, system: { managers: { id: user.id } } },
-      relations: ['keys'],
-    });
-    await this.keyRepo.softRemove(cylinder.keys);
-    return this.cylinderRepo.softRemove(cylinder);
+    const cylinder = await this.helper.getCylinderIfUserCanManage(user, cylinderid, ['keys', 'system', 'keys.cylinder']);
+    if (!cylinder) {
+      throw new HttpException('Zylinder nicht gefunden', HttpStatus.BAD_REQUEST)
+    }
+
+    const keysToDelete = cylinder.keys.filter(k => k.cylinder.length == 1);
+    await this.keyRepo.softRemove(keysToDelete);
+    await this.cylinderRepo.softDelete({id: cylinder.id})
+    return;
   }
 
   async updateCylinder(user: User, cylinder: Partial<Cylinder>) {
-    const original = await this.cylinderRepo.findOneOrFail({
-      where: { id: cylinder.id, system: { managers: { id: user.id } } },
-      relations: ['keys', 'system'],
-    });
+    const original = await this.helper.getCylinderIfUserCanManage(user, cylinder.id);
+    if (!original) {
+      throw new HttpException('Zylinder nicht gefunden', HttpStatus.BAD_REQUEST)
+    }
 
     Object.keys(cylinder).forEach((k: string) => {
       original[k] = cylinder[k];
diff --git a/api/src/modules/key/key.module.ts b/api/src/modules/key/key.module.ts
index 17b8783..cd87c38 100644
--- a/api/src/modules/key/key.module.ts
+++ b/api/src/modules/key/key.module.ts
@@ -3,10 +3,11 @@ import { KeyController } from './key.controller';
 import { KeyService } from './key.service';
 import { DatabaseModule } from 'src/shared/database/database.module';
 import { AuthModule } from '../auth/auth.module';
+import { SharedServiceModule } from 'src/shared/service/shared.service.module';
 
 @Module({
   controllers: [KeyController],
   providers: [KeyService],
-  imports: [DatabaseModule, AuthModule],
+  imports: [DatabaseModule, AuthModule, SharedServiceModule],
 })
 export class KeyModule {}
diff --git a/api/src/modules/key/key.service.ts b/api/src/modules/key/key.service.ts
index 31ea8a0..ebe7aaf 100644
--- a/api/src/modules/key/key.service.ts
+++ b/api/src/modules/key/key.service.ts
@@ -4,11 +4,11 @@ import { IUser } from 'src/model/interface';
 import {
   ActivityRepository,
   CylinderRepository,
-  KeyActivityRepository,
   KeyRepository,
   KeySystemRepository,
 } from 'src/model/repositories';
 import { KeyHandoutRepository } from 'src/model/repositories/key-handout.repository';
+import { ActivityHelperService } from 'src/shared/service/activity.logger.service';
 import { IsNull, Not } from 'typeorm';
 
 @Injectable()
@@ -17,9 +17,8 @@ export class KeyService {
     private readonly keyrepository: KeyRepository,
     private readonly cylinderRepository: CylinderRepository,
     private readonly systemRepo: KeySystemRepository,
-    private activityRepo: KeyActivityRepository,
     private handoverRepo: KeyHandoutRepository,
-    private systemActivityRepo: ActivityRepository, 
+    private readonly activityService: ActivityHelperService
   ) {}
 
   async getUsersKeys(user: User): Promise<Key[]> {
@@ -41,25 +40,9 @@ export class KeyService {
       where: { cylinder: { system: { managers: { id: user.id } } } },
     });
 
-    const original = await this.keyrepository.findOne({
-      where: { id: key.id },
-      relations: ['cylinder'],
-    });
-    this.saveLog(original, user);
     return this.keyrepository.save(this.keyrepository.create(key));
   }
 
-  private saveLog(key: Key, user: User) {
-    const l = this.activityRepo.create({
-      cylinder: key.cylinder,
-      handedOut: key.handedOut,
-      name: key.name,
-      id: key.id,
-      nr: key.nr,
-      user: user,
-    });
-    this.activityRepo.save(l);
-  }
 
   async getUsersCylinders(user: User): Promise<Cylinder[]> {
     if (!user || !user.id) {
@@ -73,7 +56,7 @@ export class KeyService {
     });
   }
 
-  async handoverKey(user: IUser, data: any, keyID: string) {
+  async handoverKey(user: User, data: any, keyID: string) {
     const key: Key = await this.keyrepository.findOneOrFail({
       where: { id: keyID, cylinder: { system: { managers: { id: user.id } } } },
       relations: [ 'cylinder', 'cylinder.system' ]
@@ -92,13 +75,7 @@ export class KeyService {
       }),
     );
 
-    const msg = `Schlüssel ${key.nr} ${res.direction == 'out' ? 'ausgegeben an ' : 'zurückgegeben von '}${res.customer.name}`
-    this.systemActivityRepo.save(
-      this.systemActivityRepo.create({
-      system: key.cylinder[0].system,
-      user: user as any,
-      message: msg,
-    }))
+    this.activityService.logKeyHandover(user, key, key.cylinder[0].system, res);
     return res;
   }
 
@@ -136,11 +113,7 @@ export class KeyService {
 
   async createKey(user: User, key: any) {
     const k = await this.keyrepository.save(this.keyrepository.create(key));
-    this.systemActivityRepo.save({
-      message: `Schlüssel ${(k as any).nr} angelegt`,
-      user: user,
-      system: (k as any).cylinder[0].system
-    });
+    this.activityService.logKeyCreated(user, key, key.cylinder[0].system);
     return k;
   }
 
diff --git a/api/src/modules/system/system.service.ts b/api/src/modules/system/system.service.ts
index 50d937a..08a64f0 100644
--- a/api/src/modules/system/system.service.ts
+++ b/api/src/modules/system/system.service.ts
@@ -10,7 +10,7 @@ export class SystemService {
   constructor(
     private systemRepo: KeySystemRepository,
     private userRepo: UserRepository,
-      private systemActivityRepo: ActivityRepository,
+    private systemActivityRepo: ActivityRepository,
     ) {}
 
   async create(user: User, createSystemDto: CreateSystemDto) {
diff --git a/api/src/modules/user/user.module.ts b/api/src/modules/user/user.module.ts
index 2b60631..cf69949 100644
--- a/api/src/modules/user/user.module.ts
+++ b/api/src/modules/user/user.module.ts
@@ -3,10 +3,11 @@ import { UserController } from './user.controller';
 import { UserService } from './user.service';
 import { AuthModule } from '../auth/auth.module';
 import { DatabaseModule } from 'src/shared/database/database.module';
+import { SharedServiceModule } from 'src/shared/service/shared.service.module';
 
 @Module({
   controllers: [UserController],
   providers: [UserService],
-  imports: [AuthModule, DatabaseModule],
+  imports: [AuthModule, DatabaseModule, SharedServiceModule],
 })
 export class UserModule {}
diff --git a/api/src/modules/user/user.service.ts b/api/src/modules/user/user.service.ts
index 7d39f38..d60859d 100644
--- a/api/src/modules/user/user.service.ts
+++ b/api/src/modules/user/user.service.ts
@@ -1,16 +1,16 @@
 import { Injectable } from '@nestjs/common';
 import { User } from 'src/model/entitites';
 import { IUser } from 'src/model/interface';
-import { ActivityRepository, KeyActivityRepository, KeySystemRepository, RoleRepository, UserRepository } from 'src/model/repositories';
-import { FindOperator, FindOperators } from 'typeorm';
-
+import { ActivityRepository, KeySystemRepository, RoleRepository, UserRepository } from 'src/model/repositories';
+import { ManageHelperService } from 'src/shared/service/system.helper.service';
 @Injectable()
 export class UserService {
   constructor(
     private readonly userRepo: UserRepository,
     private readonly roleRepo: RoleRepository,
     private readonly systemRepo: KeySystemRepository,
-    private readonly systemActivityRepo: ActivityRepository
+    private readonly systemActivityRepo: ActivityRepository,
+    private readonly helper: ManageHelperService,
   ) {}
 
   getAllUsers(): Promise<User[]> {
@@ -31,7 +31,7 @@ export class UserService {
     return this.userRepo.deleteUserById(id);
   }
 
-  async getUserStats(user: IUser) {
+  async getUserStats(user: User) {
     const systems = await this.systemRepo.find({
       where: { managers: { id: user.id }},
       relations: ['cylinders', 'cylinders.keys'],
@@ -42,10 +42,12 @@ export class UserService {
     const keys = cylinders.map(c => c.keys).flat().map(k => k.id);
     const keycount = [...new Set(keys)]
 
+    const handedOut = (await this.helper.getUsersKeys(user)).filter(k => k.handedOut).length;
     return {
       keys: keycount.length,
       cylinders: cylinders.length,
-      systems: systems.length
+      systems: systems.length,
+      handedOut: handedOut
     }
   }
 
diff --git a/api/src/shared/database/database.module.ts b/api/src/shared/database/database.module.ts
index 019acf7..8231519 100644
--- a/api/src/shared/database/database.module.ts
+++ b/api/src/shared/database/database.module.ts
@@ -5,7 +5,6 @@ import {
   Customer,
   Cylinder,
   Key,
-  KeyActivity,
   KeyHandout,
   Role,
   SSOUser,
@@ -16,7 +15,6 @@ import {
   ActivityRepository,
   CustomerRepository,
   CylinderRepository,
-  KeyActivityRepository,
   KeyRepository,
   KeySystemRepository,
   RoleRepository,
@@ -32,7 +30,6 @@ const ENTITIES = [
   KeySystem,
   Key,
   Cylinder,
-  KeyActivity,
   Customer,
   KeyHandout,
   Activity,
@@ -44,7 +41,6 @@ const REPOSITORIES = [
   KeySystemRepository,
   KeyRepository,
   CylinderRepository,
-  KeyActivityRepository,
   CustomerRepository,
   KeyHandoutRepository,
   ActivityRepository,
diff --git a/api/src/shared/service/activity.logger.service.ts b/api/src/shared/service/activity.logger.service.ts
new file mode 100644
index 0000000..2aa0c19
--- /dev/null
+++ b/api/src/shared/service/activity.logger.service.ts
@@ -0,0 +1,78 @@
+import { Injectable } from "@nestjs/common";
+import { Key, KeyHandout, User } from "src/model/entitites";
+import { KeySystem } from "src/model/entitites/system.entity";
+import { ActivityRepository, CylinderRepository, KeyRepository } from "src/model/repositories";
+
+@Injectable()
+export class ActivityHelperService {
+
+  constructor(
+    private readonly activityRepo: ActivityRepository,
+    private readonly keyRepository: KeyRepository,
+    private readonly cylinderRepo: CylinderRepository,
+  ) {}
+
+
+  async logDeleteKey(user: User, key: Key, system?: KeySystem) {
+    if (!key || !user) { return; }
+
+
+    if (!system && !key.cylinder) {
+      key = await this.keyRepository.findOne({
+        where: { id: key.id },
+        relations: ['cylinder', 'cylinder.system']
+      })
+      system = key.cylinder[0].system;
+    } else if (!system && !key.cylinder[0].system) {
+      const c = await this.cylinderRepo.findOne({
+        where: { id: key.cylinder[0].id },
+        relations: ['system']
+      });
+      if (!c) { return; }
+      system = c.system;
+    }
+
+    if (!system) { return; }
+
+    let msg = `Schlüssel ${key.nr} entfernt`;
+
+    this.activityRepo.save(
+      this.activityRepo.create({
+      system,
+      user,
+      message: msg,
+    }))
+  }
+
+  async logKeyCreated(user: User, key: Key, system: KeySystem) {
+    let msg = `Schlüssel ${key.nr} angelegt`;
+    this.activityRepo.save(
+      this.activityRepo.create({
+      system,
+      user,
+      message: msg,
+    }))
+  }
+
+  async logKeyRenamed(user: User, key: Key, system: KeySystem) {
+    let msg = `Schlüssel ${key.nr} in ${key.name} umbenannt`;
+    this.activityRepo.save(
+      this.activityRepo.create({
+      system,
+      user,
+      message: msg,
+    }))
+  }
+
+  logKeyHandover(user: User, key: Key, system: KeySystem, handover: KeyHandout) {
+
+    const msg = `Schlüssel ${key.nr} ${handover.direction == 'out' ? 'ausgegeben an ' : 'zurückgegeben von '}${handover.customer.name}`
+    this.activityRepo.save(
+      this.activityRepo.create({
+      system,
+      user,
+      message: msg,
+    }))
+
+  }
+}
\ No newline at end of file
diff --git a/api/src/shared/service/shared.service.module.ts b/api/src/shared/service/shared.service.module.ts
new file mode 100644
index 0000000..dac53c3
--- /dev/null
+++ b/api/src/shared/service/shared.service.module.ts
@@ -0,0 +1,18 @@
+import { Module } from "@nestjs/common";
+import { DatabaseModule } from "../database/database.module";
+import { ManageHelperService } from "./system.helper.service";
+import { CylinderRepository, KeySystemRepository } from "src/model/repositories";
+import { Cylinder, User } from "src/model/entitites";
+import { ActivityHelperService } from "./activity.logger.service";
+
+@Module({
+  imports: [ DatabaseModule ],
+  providers: [ ManageHelperService, ActivityHelperService ],
+  exports: [ ManageHelperService, ActivityHelperService ],
+})
+
+export class SharedServiceModule {
+
+  
+
+}
\ No newline at end of file
diff --git a/api/src/shared/service/system.helper.service.ts b/api/src/shared/service/system.helper.service.ts
new file mode 100644
index 0000000..b1b8785
--- /dev/null
+++ b/api/src/shared/service/system.helper.service.ts
@@ -0,0 +1,38 @@
+import { Injectable } from "@nestjs/common";
+import { User, Cylinder, Key } from "src/model/entitites";
+import { KeySystemRepository, CylinderRepository, KeyRepository } from "src/model/repositories";
+
+@Injectable()
+export class ManageHelperService {
+
+  constructor(
+    private readonly systemRepository: KeySystemRepository,
+    private readonly cylinderRepository: CylinderRepository,
+    private readonly keyRepo: KeyRepository,
+  ) {}
+
+
+  /**
+   * Gibt den Cylinder zurück wenn der user ein Manager ist. Gibt null zurück wenn er nicht existiert oder der 
+   * User den Cylinder nicht managen darf.
+   * @param user User
+   * @param id ID vom Cylinder
+   * @returns Cylinder | null
+   */
+  async getCylinderIfUserCanManage(user: User, id: string, relations: string[] = ['keys', 'system']): Promise<Cylinder> {
+    const cylinder = await this.cylinderRepository.findOne({
+      where: { id: id, system: { managers: { id: user.id } } },
+      relations: relations,
+    });
+    return cylinder;
+  }
+
+
+  async getUsersKeys(user: User): Promise<Key[]> {
+    const keys = await this.keyRepo.find({
+      where: { cylinder: { system: { managers: { id: user.id } } } },
+      relations: ['cylinder', 'cylinder.system', 'customer'],
+    });
+    return keys;
+  }
+}
\ No newline at end of file
diff --git a/client/src/app/core/layout/layout.component.html b/client/src/app/core/layout/layout.component.html
index 9d76345..17f75fc 100644
--- a/client/src/app/core/layout/layout.component.html
+++ b/client/src/app/core/layout/layout.component.html
@@ -15,7 +15,7 @@
     <button mat-button routerLink="/" routerLinkActive="mat-elevation-z1" [routerLinkActiveOptions]="{exact: true}">Home</button>
     <button mat-button routerLink="/keys" routerLinkActive="mat-elevation-z1">Schlüssel</button>
     <button mat-button routerLink="/cylinders" routerLinkActive="mat-elevation-z1">Zylinder</button>
-    <button mat-button routerLink="/systems" routerLinkActive="mat-elevation-z1">System</button>
+    <button mat-button routerLink="/systems" routerLinkActive="mat-elevation-z1">Schließanlagen</button>
     @if (isAdmin) {
       <button mat-button routerLink="/users" routerLinkActive="mat-elevation-z1">Alle User</button>
     }
diff --git a/client/src/app/model/interface/key.interface.ts b/client/src/app/model/interface/key.interface.ts
index 679c980..b3a9a4c 100644
--- a/client/src/app/model/interface/key.interface.ts
+++ b/client/src/app/model/interface/key.interface.ts
@@ -6,7 +6,7 @@ export interface IKey {
   createdAt: string;
   updatedAt: string;
   handedOut: boolean;
-  cylinder: ICylinder;
+  cylinder: ICylinder[];
   nr: number;
   deletedAt?: string;
 }
\ No newline at end of file
diff --git a/client/src/app/modules/cylinder/components/delete-cylinder/delete-cylinder.component.html b/client/src/app/modules/cylinder/components/delete-cylinder/delete-cylinder.component.html
index f55412d..c1e6974 100644
--- a/client/src/app/modules/cylinder/components/delete-cylinder/delete-cylinder.component.html
+++ b/client/src/app/modules/cylinder/components/delete-cylinder/delete-cylinder.component.html
@@ -1,9 +1,21 @@
-<h2 mat-dialog-title>Zylinder <u>{{key.name}}</u> löschen?</h2>
+<h2 mat-dialog-title>Zylinder <u>{{cylinder.name}}</u> löschen?</h2>
 <mat-dialog-content>
-  <p>Soll der Zylinder wirklich gelöscht werden? Alle {{ key.keyCount | number:'0.0-0'}} enthaltenen Schlüssel werden mit entfernt!</p>
-
+    <div class="warning-message">
+        <mat-icon color="warn">warning</mat-icon>
+        <p>
+            <b>{{cylinder.name}}</b> wirklich entfernen?
+            Alle Schlüssel die nur diesen Zylinder haben werden ebenfalls entfernt.
+        </p>
+        <p class="additional-info">
+            <!-- Additional information -->
+            <small>Diese Aktion kann nicht rückgängig gemacht werden.</small>
+        </p>
+    </div>
 </mat-dialog-content>
-<mat-dialog-actions>
-  <button mat-button [mat-dialog-close]="false"  >Abbrechen</button>
-  <button mat-button [mat-dialog-close]="true" color="warn">Ja, löschen</button>
+<mat-dialog-actions align="end">
+    <button mat-button [mat-dialog-close]="false">Abbrechen</button>
+    <button mat-raised-button color="warn" [mat-dialog-close]="true">
+        <mat-icon>delete</mat-icon>
+        Entfernen
+    </button>
 </mat-dialog-actions>
\ No newline at end of file
diff --git a/client/src/app/modules/cylinder/components/delete-cylinder/delete-cylinder.component.ts b/client/src/app/modules/cylinder/components/delete-cylinder/delete-cylinder.component.ts
index d997ffe..6ef5d98 100644
--- a/client/src/app/modules/cylinder/components/delete-cylinder/delete-cylinder.component.ts
+++ b/client/src/app/modules/cylinder/components/delete-cylinder/delete-cylinder.component.ts
@@ -2,17 +2,19 @@ import { CommonModule } from '@angular/common';
 import { Component, inject, LOCALE_ID } from '@angular/core';
 import { MatButtonModule } from '@angular/material/button';
 import { MAT_DIALOG_DATA, MatDialogModule, MatDialogRef } from '@angular/material/dialog';
+import { MatIconModule } from '@angular/material/icon';
+import { ICylinder } from '../../../../model/interface/cylinder.interface';
 
 @Component({
   selector: 'app-delete-cylinder',
   standalone: true,
-  imports: [MatDialogModule, MatButtonModule, CommonModule],
+  imports: [MatDialogModule, MatButtonModule, CommonModule, MatIconModule],
   providers: [{ provide: LOCALE_ID, useValue: 'de-DE' },],
   templateUrl: './delete-cylinder.component.html',
   styleUrl: './delete-cylinder.component.scss'
 })
 export class DeleteCylinderComponent {
   readonly dialogRef = inject(MatDialogRef<DeleteCylinderComponent>);
-  readonly key = inject<any>(MAT_DIALOG_DATA);
+  readonly cylinder = inject<ICylinder>(MAT_DIALOG_DATA);
 
 }
diff --git a/client/src/app/modules/dashboard/dashboard.component.html b/client/src/app/modules/dashboard/dashboard.component.html
index a13a259..71b6458 100644
--- a/client/src/app/modules/dashboard/dashboard.component.html
+++ b/client/src/app/modules/dashboard/dashboard.component.html
@@ -1,9 +1,9 @@
 <div class="dashboard-container">
     <!-- Welcome Section -->
-    <div class="welcome-section">
+    <!-- <div class="welcome-section">
         <h1>Willkommen bei Keyvault Pro</h1>
         <p>Verwalte deine Schlüssel und Systeme</p>
-    </div>
+    </div> -->
 
     <!-- Quick Stats Cards -->
     <div class="stats-grid">
@@ -38,22 +38,36 @@
         <mat-card class="stat-card">
             <mat-card-header>
                 <mat-icon>admin_panel_settings</mat-icon>
-                <mat-card-title>Systeme</mat-card-title>
+                <mat-card-title>Schließanlagen</mat-card-title>
             </mat-card-header>
             <mat-card-content>
                 <span class="stat-number">{{ systemCount }}</span>
-                <p>Aktive Systeme</p>
+                <p>Aktive Schließanlagen</p>
             </mat-card-content>
             <mat-card-actions>
                 <button mat-button routerLink="/systems">Verwalten</button>
             </mat-card-actions>
         </mat-card>
+
+        <mat-card class="stat-card">
+            <mat-card-header>
+                <mat-icon>passkey</mat-icon>
+                <mat-card-title>Ausgegebene Schlüssel</mat-card-title>
+            </mat-card-header>
+            <mat-card-content>
+                <span class="stat-number">{{ handedOut }}</span>
+                <p>Derzeit ausgegebene Schlüssel</p>
+            </mat-card-content>
+            <mat-card-actions>
+                <button mat-button routerLink="/keys">Verwalten</button>
+            </mat-card-actions>
+        </mat-card>
     </div>
 
     <!-- Recent Activity Section -->
     <div class="recent-activity">
         <h2>Letzte Aktivitäten</h2>
-        <mat-card>
+        <mat-card style="background: white">
             <mat-card-content>
                 <ag-grid-angular
                     style="width: 100%; height: 100%;"
diff --git a/client/src/app/modules/dashboard/dashboard.component.scss b/client/src/app/modules/dashboard/dashboard.component.scss
index d629631..6cb428a 100644
--- a/client/src/app/modules/dashboard/dashboard.component.scss
+++ b/client/src/app/modules/dashboard/dashboard.component.scss
@@ -1,6 +1,6 @@
 .dashboard-container {
     padding: 24px;
-    height: calc(100% - 48px);
+    height: 100%;
     display: flex;
     flex-direction: column;
     gap: 24px;
diff --git a/client/src/app/modules/dashboard/dashboard.component.ts b/client/src/app/modules/dashboard/dashboard.component.ts
index f01d084..61f428d 100644
--- a/client/src/app/modules/dashboard/dashboard.component.ts
+++ b/client/src/app/modules/dashboard/dashboard.component.ts
@@ -8,11 +8,12 @@ import {MatCardModule} from '@angular/material/card';
 import { RouterModule } from '@angular/router';
 import { AgLoadingComponent } from '../../shared/ag-grid/components/ag-loading/ag-loading.component';
 import { AG_GRID_LOCALE_DE } from '@ag-grid-community/locale';
+import { MatButtonModule } from '@angular/material/button';
 
 @Component({
   selector: 'app-dashboard',
   standalone: true,
-  imports: [AgGridAngular, MatIconModule, AgGridAngular, MatCardModule, RouterModule],
+  imports: [AgGridAngular, MatIconModule, AgGridAngular, MatCardModule, RouterModule, MatButtonModule],
   providers: [DatePipe],
   templateUrl: './dashboard.component.html',
   styleUrl: './dashboard.component.scss'
@@ -40,6 +41,7 @@ export class DashboardComponent {
   keyCount = 0;
   cylinderCount = 0; 
   systemCount = 0;
+  handedOut = 0;
   
   ngOnInit() {
     this.loadStats();
@@ -50,6 +52,7 @@ export class DashboardComponent {
       this.keyCount = stats.keys;
       this.cylinderCount = stats.cylinders;
       this.systemCount = stats.systems;
+      this.handedOut = stats.handedOut;
     });
   }
   
diff --git a/client/src/app/modules/keys/components/delete-key/delete-key.component.html b/client/src/app/modules/keys/components/delete-key/delete-key.component.html
index de34798..878fad5 100644
--- a/client/src/app/modules/keys/components/delete-key/delete-key.component.html
+++ b/client/src/app/modules/keys/components/delete-key/delete-key.component.html
@@ -1,9 +1,20 @@
-<h2 mat-dialog-title>Schlüssel {{key.name}} löschen?</h2>
+<h2 mat-dialog-title>Schlüssel <u>{{key.name}}</u> löschen?</h2>
 <mat-dialog-content>
-  <p>Soll der Schlüssel wirklich gelöscht werden?</p>
-
+    <div class="warning-message">
+        <mat-icon color="warn">warning</mat-icon>
+        <p>
+            <b>{{key.name}}</b> wirklich entfernen?
+        </p>
+        <p class="additional-info">
+            <!-- Additional information -->
+            <small>Gelöschte Schlüssel können über das Archiv wiederhergestellt werden.</small>
+        </p>
+    </div>
 </mat-dialog-content>
-<mat-dialog-actions>
-  <button mat-button [mat-dialog-close]="false"  >Abbrechen</button>
-  <button mat-button [mat-dialog-close]="true" color="warn">Ja, löschen</button>
+<mat-dialog-actions align="end">
+    <button mat-button [mat-dialog-close]="false">Abbrechen</button>
+    <button mat-raised-button color="warn" [mat-dialog-close]="true">
+        <mat-icon>delete</mat-icon>
+        Entfernen
+    </button>
 </mat-dialog-actions>
\ No newline at end of file
diff --git a/client/src/app/modules/keys/components/delete-key/delete-key.component.ts b/client/src/app/modules/keys/components/delete-key/delete-key.component.ts
index 95af08e..d99096b 100644
--- a/client/src/app/modules/keys/components/delete-key/delete-key.component.ts
+++ b/client/src/app/modules/keys/components/delete-key/delete-key.component.ts
@@ -2,11 +2,12 @@ import { Component, inject } from '@angular/core';
 import { IKey } from '../../../../model/interface/key.interface';
 import { MatDialogRef, MAT_DIALOG_DATA, MatDialogModule } from '@angular/material/dialog';
 import { MatButtonModule } from '@angular/material/button';
+import { MatIconModule } from '@angular/material/icon';
 
 @Component({
   selector: 'app-delete-key',
   standalone: true,
-  imports: [MatDialogModule, MatButtonModule],
+  imports: [MatDialogModule, MatButtonModule, MatIconModule],
   templateUrl: './delete-key.component.html',
   styleUrl: './delete-key.component.scss'
 })
diff --git a/client/src/app/modules/keys/components/handover-dialog/handover-dialog.component.html b/client/src/app/modules/keys/components/handover-dialog/handover-dialog.component.html
index 00a338f..2ce6c44 100644
--- a/client/src/app/modules/keys/components/handover-dialog/handover-dialog.component.html
+++ b/client/src/app/modules/keys/components/handover-dialog/handover-dialog.component.html
@@ -43,8 +43,8 @@
     </form>
   </mat-dialog-content>
   <mat-dialog-actions>
-    <button mat-button (click)="save()" [disabled]="handoverForm.invalid">Speichern</button>
     <button mat-button mat-dialog-close color="warn" >Schließen</button>
+    <button mat-button (click)="save()" [disabled]="handoverForm.invalid">Speichern</button>
   </mat-dialog-actions>
   </mat-tab>
 
diff --git a/client/src/app/modules/keys/components/handover-dialog/handover-dialog.component.ts b/client/src/app/modules/keys/components/handover-dialog/handover-dialog.component.ts
index 81516cb..509e27f 100644
--- a/client/src/app/modules/keys/components/handover-dialog/handover-dialog.component.ts
+++ b/client/src/app/modules/keys/components/handover-dialog/handover-dialog.component.ts
@@ -187,10 +187,17 @@ export class HandoverDialogComponent {
   createCustomer(name: string): Promise<any> {
     this.isLoading = true;
     return new Promise((resolve, reject) => {
-      this.api.createCustomer({ name, system: this.data.cylinder.system}).subscribe({
+      this.api.createCustomer({ name, system: this.data.cylinder[0].system}).subscribe({
         next: n => {
           this.isLoading = false;
           resolve(n);
+        },
+        error: e => {
+          this.isLoading = false;
+          const field = e.error.field;
+          const message = field ? e.error.message : 'Ein Fehler ist aufgetreten. Bitte versuche es später erneut';
+          this.toast.error(message);
+          reject(e);
         }
       })
     })
diff --git a/client/src/app/modules/system/components/remove-manager-popup/remove-manager-popup.component.html b/client/src/app/modules/system/components/remove-manager-popup/remove-manager-popup.component.html
index 57bd3b6..f696395 100644
--- a/client/src/app/modules/system/components/remove-manager-popup/remove-manager-popup.component.html
+++ b/client/src/app/modules/system/components/remove-manager-popup/remove-manager-popup.component.html
@@ -5,7 +5,7 @@
         <mat-icon color="warn">warning</mat-icon>
         <p>
             <b>{{ manager.firstName }} {{ manager.lastName }}</b> wirklich entfernen?
-            Der Benutzer hat dann keinen Zugriff mehr auf das System mit allen seinen Daten.
+            Der Benutzer hat dann keinen Zugriff mehr auf diese Schließanlage mit allen ihren Daten.
         </p>
         <p class="additional-info">
             <!-- Additional information -->
diff --git a/client/src/app/modules/system/components/remove-manager-popup/remove-manager-popup.component.scss b/client/src/app/modules/system/components/remove-manager-popup/remove-manager-popup.component.scss
index aa03e62..e69de29 100644
--- a/client/src/app/modules/system/components/remove-manager-popup/remove-manager-popup.component.scss
+++ b/client/src/app/modules/system/components/remove-manager-popup/remove-manager-popup.component.scss
@@ -1,19 +0,0 @@
-.warning-message {
-    display: flex;
-    flex-direction: column;
-    align-items: center;
-    text-align: center;
-    padding: 1rem;
-
-    mat-icon {
-        font-size: 48px;
-        height: 48px;
-        width: 48px;
-        margin-bottom: 1rem;
-    }
-
-    .additional-info {
-        margin-top: 1rem;
-        color: rgba(0, 0, 0, 0.6);
-    }
-}
\ No newline at end of file
diff --git a/client/src/app/modules/system/create/create.component.html b/client/src/app/modules/system/create/create.component.html
index 73b0df1..bb979b4 100644
--- a/client/src/app/modules/system/create/create.component.html
+++ b/client/src/app/modules/system/create/create.component.html
@@ -1,4 +1,4 @@
-<h2 mat-dialog-title>Neuen Schlüssel anlegen</h2>
+<h2 mat-dialog-title>Neue Schließanlage anlegen</h2>
 <mat-dialog-content>
   <form [formGroup]="createForm" class="flex flex-col gap-3">
 
@@ -8,7 +8,7 @@
       @if ((createForm.controls.name.value || '').length > 20) {
         <mat-hint>{{ (createForm.controls.name.value || '').length }} / 100 Zeichen</mat-hint>
       } @else {
-        <mat-hint>Wie soll der Schlüssel heißen?</mat-hint>
+        <mat-hint>Wie soll die Anlage heißen?</mat-hint>
       }
     </mat-form-field>
   </form>
diff --git a/client/src/app/modules/system/system.component.html b/client/src/app/modules/system/system.component.html
index 83a4783..819d61f 100644
--- a/client/src/app/modules/system/system.component.html
+++ b/client/src/app/modules/system/system.component.html
@@ -5,5 +5,5 @@
 />
 
 <div class="floating-btn-container">
-    <button mat-flat-button class="btn-create mat-elevation-z8" (click)="openCreateSystem()" color="accent" >System anlegen</button>
+    <button mat-flat-button class="btn-create mat-elevation-z8" (click)="openCreateSystem()" color="accent" >Schließanlage anlegen</button>
   </div>
\ No newline at end of file
diff --git a/client/src/app/shared/ag-grid/components/ag-delete-key/ag-delete-key.component.ts b/client/src/app/shared/ag-grid/components/ag-delete-key/ag-delete-key.component.ts
index 1cdb072..c34502b 100644
--- a/client/src/app/shared/ag-grid/components/ag-delete-key/ag-delete-key.component.ts
+++ b/client/src/app/shared/ag-grid/components/ag-delete-key/ag-delete-key.component.ts
@@ -35,7 +35,9 @@ export class AgDeleteKeyComponent implements ICellRendererAngularComp {
   delete() {
     const ref = this.dialog.open(DeleteKeyComponent, {
       data: this.key,
-      autoFocus: false
+      autoFocus: false,
+      width: '500px',
+      maxWidth: 'calc(100vw - 24px)',
     })
 
     ref.afterClosed().subscribe({
diff --git a/client/src/app/shared/api.service.ts b/client/src/app/shared/api.service.ts
index d04eb88..b76e2d4 100644
--- a/client/src/app/shared/api.service.ts
+++ b/client/src/app/shared/api.service.ts
@@ -104,8 +104,8 @@ export class ApiService {
     });
   }
 
-  getStats(): Observable<{ keys: number, cylinders: number, systems: number }> {
-    return this.http.get<{ keys: number, cylinders: number, systems: number }>('api/user/stats');
+  getStats(): Observable<{ keys: number, cylinders: number, systems: number, handedOut: number }> {
+    return this.http.get<{ keys: number, cylinders: number, systems: number, handedOut: number }>('api/user/stats');
   }
 
   getActivities(): Observable<any[]> {
diff --git a/client/src/styles.scss b/client/src/styles.scss
index 2666289..3877e25 100644
--- a/client/src/styles.scss
+++ b/client/src/styles.scss
@@ -111,4 +111,24 @@ div.ag-row {
   right: 24px;
   display: flex;
   gap: 12px;
+}
+
+.warning-message {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  text-align: center;
+  padding: 1rem;
+
+  mat-icon {
+      font-size: 48px;
+      height: 48px;
+      width: 48px;
+      margin-bottom: 1rem;
+  }
+
+  .additional-info {
+      margin-top: 1rem;
+      color: rgba(0, 0, 0, 0.6);
+  }
 }
\ No newline at end of file