Designed to open Rolex Oyster cases. The six tempered rings are precision-made to interlock so they will not slip. The sturdy cast frame fits into your bench vise and the small bar gives you the torque you need for stubborn case backs. The built in adjustable case holder fits all size watches. The L-G "Open-All" can also be used in conjunction with the L-G wrench. Ring sizes are 18.5, 20.2, 22.5, 26.5, 28.3, and 29.5 mm.