10 pack of H3 Metric Hex Drive Insert Bit Size 1. For professional application use, as well as home and DIY. 1 inch overall length, Hex Shaped Shank 1/4 inch (6.35 mm) fits in most standard sized hand held bit screwdrivers as well as power electrical and cordless drills. Made of high quality S2 Steel for long life. 10 identical bits are included in this bulk contractor pack. Works with quick-connect chucks, hand tightened chuck, and keyed chucks.