The ARTU USA 5-Pc Multi-Purpose Drill Bit Set contains sizes: 1/8", 3/16", 1/4", 5/16", 3/8". Features a chrome vanadium steel shank for enormous strength and flexibility. Works ideally for cordless drills, corded drills and drill presses. Special negative back grinding enables the tip to bore through materials with a filing action, not cutting. The blend and high tech bonding of cobalt and tungsten carbide allows bit to withstand temperatures up to 2000° F.