S Tool Steels (Shock-Resisting Steel): This includes S1, S2, S5, S6 and S7 steels. This steel can be used for things such as chisels, hammers, punches, dies mandrels, shear blades as well as driver bits. The numbers do not relate to the toughness of the steel, but rather the composition of the alIoy, as S5 has the highest impact toughness of all the tools steels. In this article we are only concerned with S2, because this is the steel that will serve you well in the following: Screw bits and any ratchet driven tools whether they are for driving screw, allen or torx equipped fasteners. Look on the side of the bit. If you can see “S2” stamped anywhere on the shaft, you can buy and use with confidence. One word of caution, if you are using your bits with an impact driver make sure they are impact rated. Impact bits are often made from different alloys to stand up to the constant impact forces being applied.