Universal Sight Base Cutter made for sights with 60° shoulder and a 3/8' base. Cuts most standard front and rear rifle sights as well as 1911 Auto low-mount, adjustable sights like E.E.A. Super Sights, Millett and current Bo-Mar. Cutter is slightly undersized at .359' which requires that you make two cutting passes to compensate for factory variations in sight manufacture and milling tolerances. Designed with proper relief for maximum strength and clean cutting. CAUTION: For use in milling machine only. 2' (5cm) long. 3⁄8' (9.5mm) diameter shank. 60° shoulder. DO NOT EXCEED 700 rpm, HIGHER SPEED WILL BREAK TEETH.