For a long time and in a number of optimization based on small models and coping with the market demand UNITED OSD painstakingly has researched and developed special small sized screw air compressor with the volume flow below 1m3/min. The small sized screw air compressor adheres to the existing features of good performance, high stability and excellent energy-saving to meet the demand of smaller air flow motive power source by enterprises and provide green products for upgrading and updating for customers to purchase on selection the small size air compressor to replace piston air compressors. It has been welcome by clients when it is released in the market.