New, unused item. This is a training device called a "wrist ball" or "swan arm," designed to tighten the upper arms and forearms, and improve grip strength. Main Features and Effects: Training Effect: Efficiently stimulates the triceps (upper arms) and forearm muscles, supporting tightening and muscle building. Mechanism: Applies the principle of centrifugal force of a hula hoop. By lightly shaking the wrist, the weight ball rotates 360 degrees along the built-in rail, creating resistance. Ease of Use: Weighs approximately 0.45kg and is lightweight. No power supply or assembly is required, and effects can be expected with use for about 3-5 minutes a day. #Diet #Training #WristBall #SwanArm