868/4 IMP DC Impaktor Square-Plus bits868 4 IMP DC Impaktor Square Plus bits Wera 868 4 IMP DC Impaktor TriTorsion Long Service Life Bit, for Square socket head screws. Impaktor bits maximise utilisation of material properties using a very special geometry designed to meet extreme working demands. The combination of a double torsion zone in the Impaktor holder and a torsion zone in the Impaktor bit results in a TriTorsion system. The TriTorsion system is designed to absorb impact forces