Master Mechanic 3/8" x 5" Black Oxide Drill Bit is a high-speed steel drill bit with a 135 split point, jobber length, straight shank, and 135-point angle with 4 cutting edges that eliminate walking and provide fast penetration. The black oxide tempering treatment reduces frictional resistance and improves chip flow. It is recommended for use in wood, plastic, wallboard, plywood, soft metals, aluminum, brass, bronze, and for occasional use in stainless steel and other hard metals.