Dog Whistle, Itery Dog Trainning Whistle to Stop Barking Ultrasonic Sound Dog Whistle Silver Color This ultrasonic sound dog training whistle is designed for dog training, the frequency produced isnt of effect on person, it will sit up, come here, eat, sit down etc Call your dog to come back even it is far from you, dogs hear whistle from up to 20000 inch away (direction and strength of wind may affect the distance) This high-quality dog accessory is made of pure copper Please be aware of this fact they are not totally silent The ultrasonic dog whistle can also be used for other pet birds (such as pigeons) to establish a good communication and discipline