840/1 Z Tamper-proof Hex-Plus BO bits, 5 x 25 mmTough viscous Wera bits for hexagon socket screws and universal use. Hex-Plus 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. Hexagon socket BO screws have a protruding pin in their drive profile. This prevents any unauthorised loosening since the ",normal", hex tools cannot move these screws. hexagon, suitable for holders as per DIN ISO 1173-D 6.3.