They feature a split style with two clearance holes and a flat on the O.D.
Global CNC type DD double duty Tool Holder Bushings are designed as a combination of the industry standard split B style tool holder bushing and the J set screw clearance style tool holder bushing.2 1/2 OD X 1.0 ID DD STYLE BUSHING They are used to adapt a wide variety of Boring Bars, Drills, Reamers and Shank type tools.