Bits drill through nails, wood, vinyl, plastics, and heavy timber. Special bit steel with machine-ground flutes and polished edges for smooth, wobble-free boring. Deep, open throat design clears chips for faster, cleaner cuts. Feed-screw pilot draws bit into wood. Full length is heat-treated and tempered. Shanks are 7/16'' hex to fit 1/2'' (13 mm) and larger three-jaw chucks. Head and twist are ground to correct clearance for easy removal from hole. For heavy construction and repair work in mines, on docks and bridges as well as electrical work.