Build strength while improving coordination in your hands and forearms with the Dyna-Flex Power Ball. Easy-grip outer sphere allows increased control and prolonged usage. Variable resistance is achieved by increasing or decreasing the speed therapeutic for hands, wrists, arms, biceps and triceps. Aids in the prevention of repetitive stress injuries and carpal tunnel syndrome. Get the edge in rock climbing and any other sport that requires control and a strong grip. The faster the unit runs, the brighter the lights will be until your whole hand is engulfed in a bright glow. Generates up to 32 lbs. of gyroscopic pressure when maximum RPMs 13,000 are reached.