LSD New Stainless Steel Adjustable Pet Dog Animal Puppy Training Supersonic Sound Clicker Whistle Obedience Safety 100% Brand New and High Quality. Adjustable pitch, simply tighten or loosen the screw to work out your dogs frequency. It should be noted that this whistle is audible to the human ear, essential for gauging its efficiency. Some tips to use the dog whistle: Adjust the pitch & blow the whistle to your dog. Even dogs can't hear all frequencies. Wait until he is asleep and gently blow on the whistle. Your whistle has a nut and screw that adjust the frequency when turned. Continue testing until your dog perks up. You will then know you have reached a frequency he can hear. Material: Stainless steel.Size(approx.): Length: 5.3cm, Dia.: 8mm