05136305001 Wera 851/4 Z 1/4'' Hex Phillips ® Power Drive Bits are high quality bits for phillips screws that feature torsion zone for the absorption of peak loads which greatly extends the product service life. Wera 851/4 Z 1/4'' Hex Phillips ® Power Drive Bits are ductile and tough for hard materials and feature Wera's Connecting Series 4. Wera 851/4 Z 1/4'' Hex Phillips ® Power Drive Bits are suitable for holders as per DIN ISO 1173-F 6.3.