840/1 BTZ bits, 4 x 25 mmBiTorsion bits for hexagon screws with elastic torsion zone into which kinetic energy is dissipated during peak loads. With softer BiTorsion zone to prevent the bit tip from twisting at high loads. This significantly increases the product life. Extra-hard design. 1/4", hexagonal, suitable for holding tools as per DIN ISO 1173-D