This series of extruders is used by manufacturers running larger lot sizes with few or no product changeovers. The HR3 Series includes our 53mm, 73mm, 103mm and 133mm extruders. 53mm. Medium lot-size custom compounding; 150 or 300 HP; 600 or 1200 RPM. 73mm. Large lot custom compounding; Up to 600 HP; 600 or 900 RPM. 103mm.