Gripmaster Hand and Finger Exerciser. Color: Green. Size: XX-Light. Challenges each finger individually using patented spring-loaded finger piston technology. Greatly improves hand wrist and forearm strength. Used by professional athletes and top fitness trainers worldwide. Fits in your pocket. Workout Anytime Anywhere. X-Light is recommended for seniors and children 12+. The patented Gripmaster is the only hand exerciser in the world that exercises each finger individually for optimum conditioning of the hand wrist and forearm.