Especially designed for Rolex oyster cases and adaptable for use with the famous L-G wrench. Will open all Rolex waterproof cases. Six knurled rings accurately interlock with the edges on genuine Rolex cases. Diameter of rings: 18.5, 20.2, 22.5, 26.5, 28.3 and 29.5 mm. Sturdy frame fits any bench vise. Adjustable case holder, built into base of frame, accommodates all size cases. Made in USA.