Injection molding is used predominantly to manufacture thermoplastic parts, and it can produce very complex parts very quickly. The mold usually comprises two sections held together by a clamp strong enough to withstand the pressure of injected molten plastic, with channels for heating, cooling and venting. Resin systems can be filled or unfilled, and using glass fibers in the resin increases the mechanical strength of the part and provides dimensional control. Typical reinforcements are chopped or milled fibers in the form of pellets. Thermosets such as bulk molding compound (BMC) are also used in compounding. Long-fiber technology, which enables molders to compound in-line with the injection processes, is also used to make a range of structural and semi-structural parts. PPG's TufRov fiber glass provides high composite strength and offers excellent processing in compounding and injection molding operations.