The wera btz bi torsion extra tough bits are harder wearing than standard bits and are ideal for difficult screwdriving jobs eg in sheet steel or metal hard reliable bit which ensures significantly extended service life over standard bits when used with a bi torsion rapidaptor the two unique torsion zones one in the bit and one in the holder work together to absorb peak loads placed on the bit significantly extending bit service life suitable for din 3126 d 63 iso 1173 bit holders use with all c