Best 526 Pet Dog Training Obedience Whistle Ultrasonic Supersonic Sound Pitch Black Quiet No.140 Pet Dog Training Obedience Whistle Ultrasonic or Supersonic Sound Pitch Black Quiet This Dog Training Whistle is designed for dog training, the frequency produced isn't of effect on person, but very useful for dogs, it will sit up, come here, eat, sit down etc. Great for recall over long distances. Key ring loop is included. Material: Metal & Plastic. Length: 90mm, Weight: 14g. Please be aware of this fact they are not totally silent. @@@ Sale only USA @@@