For use with stainless steel screws eliminates the risk of cross contaminating metals using standard tools would result in corrosion and discolouration of the stainless screw made from high grade stainless steel and vacuum ice hardened for industrial strength a torsion zone further increases the strength of these screwdriver bits contains 6x 50mm bits 2x pz2 1x tx20 2x tx25 1x hex 55mm