ACME "Silent" whistle is an excellently processed and first ever made silent dog whistle.
This model is the perfect training whistle for city or field – whether for short or long distance. The frequency is adjustable from 5400 Hz up to 12800 Hz and tunable exactly on your dog's hearing.Many animals react differently to different whistles. Each animal has different abilities to hear sounds. But most of the animals hear higher frequencies than the human ear. So, this whistle is heard not only by dogs, but also cats, horses or dolphins.
This whistle has been made by ACME since 1935. Its sound is for your dog normal to hear, but a human barely hear it even from a short distance. Very useful investment. After a short practice you will never want to miss it.