Weras bitorsion extra hard bit range is specially designed for fastening into wood the extra hardness combined with the softer bitorsion zone allows the bit to perform under the immense constant increase in torque applied when driving into wood allowing peak loads to be absorbed by the bitorsion zone avoiding premature bit breakage and enhancing 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 a