Features: -This Dog Training Whistle is designed for dog training, the frequency produced isn't of effect on person, but very useful for dogs, it will sit up, come here, eat, sit down etc. -Great for recall over long distances -Key ring loop is included -Please be aware of this fact they are not totally silent. Description Colour: Chrome Silver Material: Chrome Plated Brass Length: 5.5cm (approx.) Key ring loop included 1 Whistle 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. Notes: 1 inch = 2.54 cm 1. Please allow 0.5-1CM differs due to manual measurement. 2. Real color may slightly different from pictures due to computer screen's resolution, brightness, contrast etc. This Dog Training Whistle is designed for dog training, the frequency produced isn't of effect on person, but very useful for dogs, it will sit up, come here, eat, sit down etc. Great for recall over long distances Key ring loop is included Please be aware of this fact they are not totally silent.