Wiha's Drive-Loc systems introduce a great feature to help you get more out of your tools. The Drive-Loc system allows you to change the length of your screwdriver blade to make it as long - or as short as you need for a job. The Drive-Loc locks into place incrementally with spherical dimples for a precise length. Drive-Loc blades are double-sided hex-blades and the Drive-Loc 6 is equivalent to a 6mm bit.