Ideal for knockouts in electrical junction boxes and cabinets. Convenient 1/4" hex shank for quick bit changes with Impact. Durable high speed steel construction. Drills perfectly round holes in materials such as steel, brass, plastic, and wood. Makita Step Drill Bit is manufactured from high speed steel for longer life. Step Bit efficiently enlarges and deburs holes. 1/4" hex shank for convenient use with both Impact Drivers and Driver-Drills.