Product Description: Dog whistle: this is one of the most useful tools used to bring back a dog. Not only does sound of a tube form dog whistle that humans can hear, but it also produces ultrasonic frequencies that only dogs can hear. This frequency ultrasound is so far away that the dog can hear it in the distance.Ultrasonic wave: ultrasonic energy is large and propagated along the straight line. The ultrasonic waves emitted by the dog whistle can be clearly identified by the dog. The owner can use the dog whistle to blow out different tones to give instructions.Depending on the rhythm of the sound, you can let the dog understand the meaning of each rhythm and the instructions given.How to train your dog?1. Using a different flute method to specify "don't move" "sit " "come " and so on. When teaching the dog these movements, play the dog flute according to the regulation, then teach him to do the corresponding action. Train again and again, and your dog will know what to do when he she hear the sound of the dog whistle.2. The dog's behavior according to your instruction need to be trained. Such as, at meal time, blow on the whistle before they get the food. It will only take a few times of doing this and your dog will react quickly.Size: 7.7x0.6cm Material: copper nickel plating Colors: red, blue, black, white, purple, yellow (optional) Package includes: 1 *Dog Whistle Note: 1. Due to manual measurement, please allow a small error. Please make sure you don't mind before bidding 2. Colors may vary depending on the display. Please understand Note: Hello, please pay attention to your shipping address when purchasing products. If your receipt information (such as name, street, house number, doorbell/email without name, etc.) is incorrect, the order will not be delivered correctly