Wera 840/4 Z Bits – 6 x 89mm. Tough viscous Wera bits for hexagon socket screws for universal use. The Hex-Plus profile offers a greater contact surface in the head of the screw.The notching effect is therefore reduced to a minimum and damage to the screw head more or less eliminated. 1/4″ hexagon suitable for holders as per DIN ISO 1173-F 6.3.