The pellet mill consists of three parts: forcing a soft material through holes in a metal die plate, forming compacted pellets and cutting the compacted pellets into pre-determined size. The machinery which has been developed for this purpose is now very diverse in design and there is much controversy between different equipment manufacturers as to which type is the most effective. Most pellet mills now have one or more conditioning units mounted above them where liquids such as water can be added to improve pelletability. The water is sometimes added in the form of steam, resulting in firmer pellets.