MIBRO 36-Piece Screwdriver Bit, Bit Holder and Nut Setter Set is ideal for general-purpose fastening for DIY projects and general home use. This set includes thirty-one 1 in. screwdriver bits made from quality chrome vanadium (CrV) steel, which properly balance hardness and torque and ensure an exact fit in the screw head. One 2-3/8 in. Magnetic Bit Holder which features a 1/4 in. quick change hex shank for a secure fit in the drill or hand driver and can be used with quick-change drill-drive chucks. 4 non-magnetic nut setters (1/4 in., 5/16 in., 3/8 in. and 7/16 in.) for fastening hex-head bolts and nuts. Most common sizes included. Forged from premium CrV steel, they will ensure a secure fit on the fastener and drive the project to completion.