Wera 05346286001 853/4 1/4'' Hex Phillips ACR Power Drive Bits are high quality bits with Torsion zone - where kinetic energy is diverted from peak loads. This greatly extends the product service life. Wera 853/4 1/4'' Hex Phillips ACR ® Power Drive Bits feature rough ribs (anti-cam out feature) to prevent any slipping out of the screw head. Wera 853/4 1/4'' Hex Phillips ACR ® Power Drive Bits are tough and viscous for universal use and are suitable for holders as per DIN ISO 1173-F 6.3.