Tapered drill with widened flutes for drilling fast, clean pilot holes.. Adjustable four-cutter counterbore cuts and clears chips quicker for fast, smooth countersinking.. Counterbore attaches to flats on shank with two hex screws for a secure fit, and can be adjusted for controlled pilot hole depth.1/4 in. quick-change shank reduces slipping in standard chucks and is compatible with all 1/4 in. quick-change chucks, including impact drills.