851/4 BDC bits, PH 2 x 50 mmBiTorsion bits for Phillips screws with tiny diamond particles on the bit tip. This ensures a secure fit of the bit in the screw, reduces the contact pressure required and lowers the risk of slipping. Comes with Torsion zone where kinetic energy is diverted from peak loads. This greatly extends the product service life, hexagon, suitable for holders as per DIN ISO 1173-F 6.3.