About the oil mist eliminator exhaust filter assemblies: The compact oil mist eliminator exhaust filters come with the internal filter media installed and are used to capture oil fog, mist, or smoke from the exhaust of oil vacuum pumps. These exhaust filters are air tight to prevent the vacuum pump exhaust vapors from leaking into your laboratory. They have KF25 (NW25) ports for easy connection between your vacuum pump and exhaust line. These oil mist exhaust eliminator filters are made of chrome plated steel construction to prevent rusting and has internal oil drain-back to return the captured oil back in to the vacuum pump. Each comes with an installed filter media that's easy to replace with a thumbscrew.