GERMAN DE LUXE SILENT WHISTLE
DELUXE SPRENGER SILENT WHISTLE The Sprenger silent whistle uses ultra-sound and is very effective for dog training. It is adjustable and dogs can pick up the sound to a distance that varies between 150 and 400 meters, depending on the wind direction. It comes with a plastic case which prevents the screw from turning on itself. The whistle is 3 1/4” long.