5/16” hex x 1/4 square drive Magnetic socket for hexagon head screws, bolts etc Used in conjunction with a power drill/driver to allow easy fixing of 5/16 head tek self drill screws Ideal for use hex self drill screws. 22mm length 1/4 Square drive Ideal for using with extension bars (see part number MA1414152 & MA1414203) for reaching deep applications.