Air leaving a compressor is hot, dirty, and full of moisture, which can damage and shorten the life of downstream equipment, such as valves, cylinders and pneumatic air tools. Before this air can be used, it needs to be cleaned and lubricated. This 3 stage combination unit does exactly that. An airline filter cleans compressed air. It strains the air, traps solid particles (dust, dirt, rust) and separates liquids (water, oil). Filter (stage 1) is installed in the air line upstream of regulators, lubricators, directional control valves, and air driven devices and tools.