This Compact Oil Mist Exhaust Filter comes with Filter Media and captures oil fog, mist or smoke from exhaust of oil flooded vacuum pumps. Comes with auto drain back design for recycling of oil mist. The internal drain returns oil back into the pump, prevents oil blow back with auto sealing and with an enclosed housing allows for a clean environment. Steel construction with Nickel plated finish. Seamless drawn housings and no welds to rust or vibrate apart. Comes with filter media that's easy to replace with a thumbscrew. Fits Welch Belt Drive pumps 1397 and 1374.