Wera screwdriver bits are designed for tough applications found in both Trade and Industry. Strictly controlled manufacturing processes helps fulfill the highest quality requirements. They provide the transfer of high torque values and deliver a long service life. Bi-Torsion screwdriver bit , BDC series diamond coated. Colour banded for identification. The coating helps prevent cam out damage to the head of screws. The material used also ensures longer life span. 1/4in Hexagon drive