YueYueZou&reg; Hand Exerciser for Guitar, Piano, or Therapy, Finger Training Develops and maintains the strength and dexterity of your fingers, hands and forearms Practice without your instrument anywhere anytime, it could be use for strengthen palm, fingers, wrists and other area of hand. The resistance levels could be adjustable, suitable for the auxiliary exercise of instrument playing, physical exercise and other activities. Compact and ultra-light design means you can carry it in your pocket, bag or instrument case. Reversible molded grip uncovers simulated strings to help develop and maintain finger calluses for string musicians