Weras bitorsion extra tough bit range is specially designed for fastening into metal the extra durability combined with a softer bitorsion zone allows the bit to absorb the sudden increase in torque applied when a screw comes to a stop in metal the bitorsion zone avoids premature bit breakage and enhances the service life of the bits the bitorsion system means that the bit has been precision hardened to allow the metal to flex slightly in controlled areas and absorb the stresses applied by a