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. The set contains a 58mm professional magnetic bit holder plus 1 x 5.5mm slotted bit, 1 x each Pz1 and Ph1, 3 x Ph2 and 4 x Pz2, and 1 x each Ph3 and Pz3. The bit holder is impact resistant, glass-fibre reinforced polyamide, tough and reliable it will keep the bits safely stored until required.