FA-10P Guitar Bass Piano Extendable Hand Exerciser Finger Strengthener Trainer - Black Spring-loaded finger piston technology, the ultimate conditioning tool for all musicians Develops and maintains the strength and dexterity of your fingers, hands and forearms Perfect tool for pre-show warm-ups Greatly improves hand, wrist, and forearm strength Compact and ultra-light design means you can carry it in your pocket, bag or instrument case