Straight, Double Fluted Step Drill Bits From Klein Tools Provide Cleaner Cutting and Drilling. The Aluminum Titanium Coating Is 10 Times More Durable Than Steamed Black Oxide For Longer Bit Life. 3/8-Inch Hex Shank Is Durable, and Has A Firm, Positive Grip. Laser-Etched Markings Provide Quick Size Identification On Primary Holes. This Step Bit Has 12-Hole Sizes From 3/16-Inch to 7/8-Inch (4.8 to 22.2 MM).