Automatic activation: The updated version features a built-in pre-tensioning mechanism, eliminating the need for a cable. Press the inner ball with your thumb, then slide your thumb in the direction of the arrow to activate the internal spring. The principle of operation is simple and environmentally friendly. When the wrist rotates, the ball rotates at high speed, creating centrifugal force that provides noticeable resistance to the wrist.Suitable for support: especially useful for those who frequently use computers or mobile phones, or suffer from conditions such as carpal tunnel syndrome and repetitive strain injuries. By continuously and indirectly strengthening the muscles and flexibility of the forearm and wrist joints, it significantly increases muscle strength, flexibility, and promotes blood circulation.Improved design: the wrist ball is portable, suitable for use in the office, gym, or at home. It can also serve as a stress-relieving toy while providing finger grip strength training.Stylish gift: the rotating ball is a great gift for children who are interested in sports, restless adults, office workers, guitarists, pianists, and other musicians.Quality guarantee: Each ball undergoes rigorous testing on factory equipment, inspection in the warehouse, and re-inspection by hand. No batteries are required for this product. The interaction between the rotation of the wrist and the core of the ball creates a centrifugal force that supports