Versatile whistles, the ferrules can fasten your keys together, avoid misplacing or losing your dog whistle, convenient to carry and keep. It is small and light weight,You can put it on a key chain or pocket. Dogs can't hear all frequencies, but you can adjust the pitch for corresponding frequency to fit your dog the best. You never have to worry about losing your dog whistle due to our free top-quality Lanyard Strap. Dog whistles are very popular and proven to be an effective mechanism to train your dog without hurting your pet through shocks and other means.