Tool steels are steels used to make tooling. Tooling can be a punch for a punch and die set (left), a knife blade roller for a shear press (right), or a mold cavity for a plastic injection mold (below). There are hundreds of applications for tool steels. The most common heat treatable tool steels are W type which is quenched in water, A type which is quenched in air, and O type which is quenched in oil.