Wera 05134372001 851/4 A 1/4'' Hex Phillips Power Drive Bits are high quality bits for phillips screws that feature a sharp-edged profile that ensures a dependable transfer of power between the bit and the screw. Wera 851/4 A 1/4'' Hex Phillips ® Power Drive Bits are particularly hard for semi-hard materials and are designed with Wera's Connecting Series 4 and are suitable for holders as per DIN ISO 1173-F 6.3.