The Cornwell Quality Tools TEMPEST Drill Bits are designed to easily drill complete holes or enlarge existing holes through hardened steel, stainless steel, aluminum, and grade 8 bolts. Due to their serrated cutting/step drill edge geometry, the bits run cooler with less friction. Additionally, while their stepped tip prevents the bit from walking on rounded surfaces, their three shank design eliminates slippage. Sizes range from 1/16” to 1/2”. They are made from heat treated M2 high-speed steel and are made in the U.S.A.