Material: Stainless steel Length: 5.2cm (approximately) Package includes: 1 piece Note: The dog whistle consists of two parts. Part 1: Ultrasound. Human ears cannot hear you, but dogs can hear you. Part 2: These soft sounds can be heard by humans, which helps the owner to play the flute or piccolo to train them The tone is adjustable, just tighten or loosen the screw to calculate your dog's frequency. It should be noted that the human ear can hear this whistle, which is essential for measuring its efficiency. Some tips for using dog whistle: Adjust the pitch and whistle for your dog. Even dogs cannot hear all frequencies. When he fell asleep, blew the whistle softly. Your whistle has a nut and bolt to adjust the frequency as it turns. Continue testing until your dog recovers. Then you will know that you have reached a frequency that he can hear. Use different sequences of dog whistles to train your dog. For example, a prolonged outburst may mean ""come"", while a series of short and intermittent outbursts may mean ""sit down."" Keep your whistle commands consistent, and your dog will always know what you expect of him. According to your instructions, the dog's behavior needs to be trained. How, at mealtime, whistle before they get food. It only takes a few times to do this, and your dog will react quickly.