... LED: 6pcs a grade led Item No.: 868NC Product name:Wrist ball with LED and COUNTER Description:Shell material: A grade PCRoller material: Zinc ... inside the device, it is powered by rotating the wrist, and the speed of rotation can reach over 12000 R.P ... for sports like golf,tennis,squash,cricket,baseball,bowling,basket ball,motocross,mountain climbing.-Increase strength in fingers, wrists,hands, ...