Broken drill bits are a waste of time. Makita Black Oxide Drill Bits are designed for use with today’s high-torque drills and impact drivers, and engineered for added durability for longer service life. The durable one-piece design is constructed with High Speed Steel (HSS), with a ¼” hex shank for use with impact drivers and driver-drills. Makita Black Oxide Drill Bits are ideal for drilling holes in ferrous metal, wood, plastic, non-ferrous metal, and cast iron.