High quality BiTorsion holder by Wera for use with a ratchet or power screwdriver; with 1/4" square drive. The strong magnet holds the bits absolutely securely. Energy from peak loads is diverted into the BiTorsion zone to considerably reduce the danger of breakage and prolong the service life. Optimum results with the BiTorsion system by using both the holder and bits. Suitable for bits with 1/4" hexagon drive as per DIN ISO 1173-C 6.3 and E 6.3.