Athena United AUSTDBIT Titanium Step Drill Bit 1/4 to 1-3/8" Step sizes:1/4", 3/8", 1/2", 5/8", 3/4", 7/8", 1", 1-1/8", 1-1/4" and 1-3/8" Works on plastic, wood and most metals, including steel, brass, aluminum and copper Titanium coated heat treated high quality steel