Specifications: Standard 3/4" Shank with flats at 90°. Annular (Hole) Cutters enables you to cut a burr free hole. It penetrates rapidly, cutting only the periphery of the hole thus allowing the pilot pin to eject the center plug of steel. Cutters are interchangeable with other standard hole cutting systems. M35 cobalt, fully ground. Cobalt cutters have unique geometry which provides faster feed, less friction & smooth hole finish.