What better way to train your dog than with the Acme 210.5 Dog Training Whistle. This ultra-high pitched whistle is ideally suited to Spaniels with a single frequency of 5900Hz. Perfect for dogs who are hard of hearing, this whistle is very audible and lets your dog know he needs to perk up and listen. Molded from high-impact symonite plastic, these whistles are shatterproof and bite resistant. Acme training whistles are the most popular dog training whistles in the world because they’re simple, easy and withstanding.