The Sport-Thieme punching ball Power Spin: Improve your boxing technique - The Sport-Thieme punching ball Power Spin is a boxing trainer with a padded arm for additional arm and leg work. The base can be filled with water or sand. The punching ball is attached to a spring, which ensures a fast and precise pendulum motion. This training device trains boxing technique and evasiveness, and improves speed, reaction and coordination. The bar is height-adjustable and can therefore be customised to the height of the user.