Features: * Simple to start with a pull-string. * The faster you spin it, the harder your muscles work. * Internal LED bulbs light up when the ball is in motion. * Small, compact, and portable; you can take it anywhere. * Powered by rotating the wrist, the speed can reach up to 12,000 RPM. * Rehabilitates sore muscles and joints, great for musicians, guitarists, pianists, and drummers. * Increase the speed by making a rotational wrist movement and keep in sync with the ball's spinning. * Strengthens fingers, wrists, hands, forearms, shoulders, and biceps, and also promotes coordination and blood circulation. Specifications: * Material: PC + PP * Size: 7cm (Dia.) Package list: * 1 * Wrist ball Notes: 1. Manual measurement, please allow for a 1-3mm error. 2. Due to the difference between different monitors, the picture may not reflect the actual color of the item. We guarantee the style is the same as shown in the picture.