Wera 05059855001 851/4 TH 1/4'' Hex Phillips Power Drive Bits are high quality bits with torsion zone for absorption of peak loads which greatly enhances the service life of the bits. Wera 851/4 TH 1/4'' Hex Phillips ® Power Drive Bits are particularly hard for semi-hard materials and feature Wera's Connecting Series. Wera 851/4 TH 1/4'' Hex Phillips ® Power Drive Bits are suitable for holders as per DIN ISO 1173-F 6.3.