The Perfect Pitch That Musicians Always Want - on a key chain! The Pocket Tones are a handy, durable and compact device, which may be carried in your pocket or purse as a key fob: or they fit conveniently in an instrument case for accurate tones whenever you need them. Use pocket tones to develop excellent pitch recognition - it is the perfect answer for the intermediate tone, and it is always at hand. They are available for a variety of instruments including the guitar, mandolin/violin, cello/tenor banjo, and 5 string banjo.