Moisture and oil separators are an unbeatable combination for helping you get professional results. Together, they will remove 99.9% of the contaminates that can ruin paint jobs and painting equipment. The oil separator is a coalescing type and filters particles as small as 0.3 microns. The moisutre separator ensures dry air to the gun and takes out particulates down to 40 microns. Both have 1/2in. NPT ports and handle up to 150 p.s.i.. Use both, connected in series, for best results.