This 20-piece insert bit set includes insert bits made of high grade S2 tool steel for long life and extreme durability. The unique case provides individual storage for the insert bits as well as storage for the drive guide. A magnet on the under side of the case allows it to be attached to most metal tool boxes, job storage boxes, truck boxes or other metal surfaces for quick and easy access - the set can be stored where it won't get buried by other tools or accessories. Set includes (19) of the most commonly used screw driver bits (Phillips®, square drive, TORX® and slotted), magnetic drive guide and magnetic storage case. Milwaukee® Insert Bit Puck Set, Magnetic, 20 Piece, Specifications: 1/4 in Hex Shank, S2 Steel