Wera 05057725001 851/2 Z 5/16'' Hex Phillips Insert Bits are tough and viscous bits designed for phillips screws. Wera 851/2 Z 5/16'' Hex Phillips ® Insert Bits are designed ductile and tough for hard materials, feature a 5/16'' hex using Wera's Connecting Series 2 and are suitable for holders as per DIN ISO 1173-D 8.