Irwin 1882793 Countersink Bit Set, Specifications: 1/4 in Shank, HSS, Includes: #6, #8, #10 Countersinks

Tapered drill with widened flutes for drilling fast, clean pilot holes. Adjustable four-cutter counterbore cuts and clears chips quicker for fast, smooth counter sinking. 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. Set includes one small depth stop, one #6, one #8 and one #10 bit.