These Double-Fluted Step Drill Bits provide faster cutting and drilling than single flute bits. The easy-to-read step markings and targets save time when drilling holes. Thick 3/8-Inch hex shank provides a firm, positive grip and won't spin out in the drill. 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 9-hole sizes from 1/4-Inch to 3/4-Inch (6.4 to 19.1 mm). High-visibility silver targets for primary hole sizes Thick 3/8-Inch hex shank won't round out in the drill chuck for a more positive grip 9 hole sizes 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 9-hole sizes from 1/4-Inch to 3/4-Inch (6.4 to 19.1 mm).