The six tempered rings will fit every existing size and because they are precision-made to interlock 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 “Openall” can also be used in conjunction with the L-G wrench. Ring sizes are 18.5 20.2 22.5 26.5 28.3 29.5mm. Made in the USA.