The ACME Silent Shepherd's whistle is the ultimate whistle for training and commanding both working and domestic dogs.
Almost inaudible to the human ear, but clear to your dog up to one mile (1.6 km) away, even when there is a lot of ambient noise from traffic or other activities.
This whistle also incorporates an adjustable frequency device giving a range of 7400 hertz. A locking screw secures it at your chosen frequency.
This whistle was invented and pioneered by ACME in 1935, and now comes complete with a leaflet 'How to Train Your Dog'.