This the Norgren oil removal filter we use in our on board air supply kits.
These filters are all aluminum body and bowls, 3/8″ npt female ports.
The bowl is equipped with the automatic float drain system, when the filter bowl collects a small amount of oil it automatically opens the drain and pushes the oil to return to the compressor.
The drain fitting is 1/8″ pipe thread.
The float/drain assembly is available separately as a service item.