HITOP Dog Whistle to Stop Barking - Silent Bark Control for Dogs - Black Training Whistle Ultrasonic Patrol Sound - Train Your Dog STOP BARKING - Use it to call your dog or train to stop barking. Change frequencies since different dogs respond to different frequencies TRAINING WHISTLE - Teach your dog commands and let him learn basic hand movements while whistling different times for each command TAKE CONTROL - Control your dog whenever he gets out of line and make it listen and obey. Once your dog learns the commands, you will have full control no matter hwere you are DIRTY PROTECTION- Includes a cover that goes over the whistle so that it is not exposed and protected at all times. Keep dirt away from the whistle by using this plastic whistle cover Package included: 1*Dog Whistle