You may have noticed these in other workshops and wondered what they are for. The rubber case ball is a novel but very effective tool. Pressing the ball down on a screw type case back creates a strong friction grip. The case back can then be unscrewed by turning the ball. The ball is most effective for quick unscrewing of backs which are not overly tight. An added bonus is that it won’t scratch the case or case back. Particularly useful for gold screw backs.