Wera 05056500001 851/1 Z 1/4'' Hex Phillips Insert Bits are tough viscous bits for phillips screws designed for universal use. Wera 851/1 Z 1/4'' Phillips ® Insert Bits are ductile and tough for hard materials and are designed to prevent premature breakage of the drive tip. Wera 851/1 Z 1/4'' Phillips ® Insert Bits feature a 1/4'' hex drive and feature Wera Connecting Series 1 and are suitable for holders as per DIN ISO 1173-D 6.3.