D’Addario Varigrip Adjustable Hand Exerciser (PW-VG-01)

Develops and maintains the strength and dexterity of your fingers, hands and forearms
Variable tension provides customized conditioning for individual fingers
Reversible molded grip uncovers simulated strings to help develop and maintain finger calluses for string musicians
Perfect tool for pre-show warm-ups and maintaining conditioning when away from your instrument
The ultimate conditioning tool for all musicians