The Acme Silent Dog Whistle is traditionally known as silent, this whistle is still audible to dogs and humans at certain pitches. This whistle is excellent for dog training but has proved to be popular with people who have issues with noisy dogs.Silent Dog Whistle FeaturesFully adjustable silent dog whistleTop in the marketComplete with instructionsAdjust to your dogs hearingWith chain-linked cover for protection of mouthpieceAcme\'s Ref.MPN: ACSDSizes: One SizePM Ref: 96572