Description: Designed for training dog Brass construction with nickel finished Turn the nut and screw that adjust the frequency to fit your dog Handy split ring for attaching to key ring or land yard Convenient to use and carry out with key ring loop Specification: Condition:Brand New Material:High quality Brass Color:Silver Size:approx.5.5cm long Package included: 1/2/3pcs Dog Whistles Note: The dog whistle is in 2 parts. Part 1: Ultrasonic. Inaudible to the Human Ear, but very audible to the dog. Part 2: Audible Element, this can be heard by the Human Ear, which helps the owner to distinguish long and/or short whistles to train their dog. 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.