[Product Name]: Adjustable Pet Training Dog Whistle [Product Material]: Copper[Product Size]: 5.3CM, diameter 6mm[Product Overview]: The dog flute is one of the most useful gadgets for reminding dogs. It is a completely different product from the flute we play. The dog whistle emits a kind of ultrasonic sound which is not easily detectable by the human ear but is very obvious to dogs. Because dogs’ ears can receive 120kHz sound waves, while people can hear 20kHz at most. In addition to the tubular sound that can be heard by humans, the dog whistle also emits sounds that cannot be heard by humans. Only dogs can hear the frequency. Ultrasounds at this frequency can travel far, so dogs can travel far. Somewhere to hear that sound. The dog whistle made using this specialty of the dog can easily remind the dog that ran away after chasing the prey. [How to use] : Loosen the sonic adjustment screw. While blowing air from the air inlet, rotate the adjustment rod. Once the adjustment rod is