The assembly of the upper and lower die shoes ( punch and die holders), usually including the guide pins, guide pin bushings, and heel blocks. This assembly takes many forms, shapes, and sizes and is frequently purchased as a commercially available unit. Two (or, for a mechanical upsetter, three) machined dies used together during the production of a die forging.

In stamping, the parts of the press that hold the die and locate it in proper relation to the punches.