Wera 05134382001 851/4 TZ SB 1/4'' Hex Phillips Power Drive Bit (2-Pack)s 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 TZ 1/4'' Hex Phillips ® Power Drive Bits are ductile and tough for hard materials and feature Wera's Connecting Series 4. Wera 851/4 TZ 1/4'' Hex Phillips ® Power Drive Bit are suitable for holders as per DIN ISO 1173-F 6.3.