Material: stainless steel, service life is much longer than old ones. The interface has a locking mechanism, a built-in, automatic magnetic head. 1/4" (6.35mm) hex shank, Length: 60mm / 100mm / 150mm (2", 4", 6" )Portable and small bit holder extension set, to meet your various needs Used in the installation of pneumatic screwdriver, electric screwdriver, pneumatic drill, manual screwdriver and other installation for the hex tool . It is a good accessory for conversion. Built-in magnetic (only the bottom of the holed part), quick quick release will greatly improve work efficiency. Hexagonal shank 1/4" easy to use, quick change and fits all drills, 1/4" impact drivers and hand screwdrivers. Note: Only the bottom of the hole part is magnetic, the hexagonal rod is NOT magnetic. Only for single head hex drill bits.