3/16" To 1/2", Step Drill Bit, Jam Free Performance Features Dual Flute Design Provides Greater Speed & Control, Up To 2 X Faster, Optimized For Cordless Drills In High Speed, Rapid Strike Tip Creates Fast, Accurate Starts & Generates Less Heat, Optimized Geometry With Black Oxide Coating To Cut Faster & Produce Less Heat, Laser Engraved Reference Marks Easily Stops On Any Hole Size, 3 Flat Secure Grip Shanks Reduces Bit Slippage In The Chuck, 1/16" Increments, 6 Steps, 1/4" Shank, Metal/Plastic Applications.