3 Inch Milwaukee Shockwave Magnetic Bit HolderBit holders and nutsetters set screws and nuts. Bit holder and nut setter varieties are designed with universal quarter inch hex shanks to fit most power tools. A bit holder is used with a hex insert bit and a magnetic nut driver can provide a reliable grip on metal screws and other hex head fasteners. A hex driver screw guide features a retracting sleeve to help steady long fasteners and can work great for hard to reach applications.