Exercises Wrists and Hands spins at up to 15,000+ RPM to exercise and strengthen wrists and hands. You’ll feel the burn in just a minute of spinning. This certainly requires some fine motor skills in order to use. The dominant hand/arm was easily able to keep the ball going, that it will help refine your fine motor skills in that non-dominant hand/arm. Made with a military-grade plastic shell, a break-resistant structure and reversible inner tracks for 2X lifespan. No batteries required, you can get a challenging, strengthening workout anytime, anywhere, even on your lunch break. Exercise your fingers, wrists, hands, forearms, shoulders, increase your arm strength. Self-starting, no cumbersome, easy to use, cool lights design, Metallic core burning cool lamp the design of the cool colorful lights does not require charging and batteries, and the physical power generation is preferably made of zinc alloy. The weight is moderate and does not hurt your hands. Power output effect diagram the principle of physical centrifugal mechanics, the rhythm and speed of the core rotation can be adjusted through artificial control, the faster the speed, the greater the f3. Product Specification: Color: Blue, Red, Colorful Weight: 450g Material: Plastic Size: 7 x 7 x 5 cm Power Supply: Magnet Function: Wrist Strength Device Package Inclusion: 1 x Wrist Power Ball