With this high-performance dog-training whistle you can order your pet back from a distance of 3 km without annoying anyone, as the frequency (adjustable from 5400 to 12800 Hz) is almost inaudible for the human ear. Made by ACME Whistles who were also responsible for developing the first dog whistle ever in 1935. This is an improved version of the first "Silent Dog Whistle". Nickel-plated brass. Length 8,5 cm, 1 cm dia. Weight 35 g.