These high grade chrome-vanadium steel bits are through hardened extra hard. This process creates an extremely hard wearing screwdriver bit. A second heat treatment creates a torsion zone between the tip and hex body. This torsion zone absorbs the shock of sudden loads, minimising the risk of fracture under high levels of stress. The combination of the two features offers you a bit that will last significantly longer. These bits are supplied in a reuseable plastic case.