Overview Reviews Product Description Engineered with a high-speed steel speedpoint tip for fast starts, the Unibit® #12 3/8"Hss fractional step drill bit makes true round holes every time.It's ideal for general use on materials such as mild steel, copper, brass, aluminum, plastic, wood, and laminates.The single-flute cutting edge allows greater control through steps, and the 7/16"Hex-shaped shank offers a secure fit. Irwin Tools Catalog Product Videos Custom Field Manufacturing country US Product Reviews Write a Review Write a Review × Irwin UNIBIT® 3/8" #12 High Speed Steel Self-Starting Step Drill Bit 10312ZR Rating * Select Rating 1 star (worst) 2 stars 3 stars (average) 4 stars 5 stars (best) Name Review Subject * Comments *