Customisable set containing highly robust bits that are ideal for heavy duty applications, even withstanding the high power of impact drivers. Features an extended torsion zone that makes it extremely sturdy for long lasting work. S2 modified steel and an optimised heat-treatment process provide extra-tough endurance for high performance. ¼" external hex shank for use with drill drivers, screwdrivers and especially impact drivers. Click-fitting slots secure individually purchased packs for a personalised collection and the easy replacement of packs.