Planet Waves Varigrip - Planet Waves introduces the ultimate conditioning tool for musicians: the Varigrip Adjustable Hand Exerciser. Designed to develop and maintain hand and finger strength, condition and dexterity, the Varigrips ergonomic design and variable tension provides customized conditioning for individual fingers, the entire hand, wrist, and forearm. The reversible moulded grip uncovers simulated strings to help develop and maintain finger callus when you are away from your instrument.