Material: Polycarbonate, Zinc Alloy Self-starting wrist power ball: Decompression and fitness anytime, anywhere, mechanical self-starting / metal ball center / variable speed lights / bass noise floor. Wrist power ball, a new generation of office decompression necessary small objects purely mechanical, without electricity, feel the power brought by the rotation of the sphere with the rotation of the wrist, the cool lights become more and more dazzling according to the rotation speed, the game of power and beauty makes people feel Immerse yourself in it. Pure mechanical structure, no need for power supply, it starts in five seconds. The greater the rotation speed, the greater the control force required, which is suitable for different groups of people to exercise. Long-term use of the wrist ball will effectively exercise the muscles of the entire arm, help relieve muscle discomfort and strain caused by long-term use of the wrist and arm, and also help fitness enthusiasts carry out targeted arm strength training.