Self-Starting Gyroscopic Forearm Exerciser Forearm Gyro Ball Wrist Exerciser Hand Wrist Forearm Trainer for Strengthen Arms Fingers Bones and Muscles. Features automatic LCD display, high-strength metal structure, built-in spring core design, adjustable resistance training, and ergonomic anti-slip grip. Origin: Mainland China, Product size: 80.00x80.00x80.00mm/3.15x3.15x3.15inch, Sports scene: muscle relaxation, Type: wrist strength ball, Training part: Wrist, Material: Plastic.