The RV Gas Ballast Oil Drain Kits continuously return the oil trapped in the EMF Oil Mist Filter to the pump. When fitted, the pump will operate as if the gas ballast control is in position II (high flow position). You can adjust the gas ballast flow rate by using the following procedure on Page 5 Sec. 2.3 of the instruction manual. This reduces oil loss from the pump and minimizes the need to check the pump oil-level and to refill the pump with oil. This is the oil return kit only, EMF oil mist filter and pump sold separately. The installation instruction manual can be downloaded in PDF format in the AVAILABLE DOWNLOADS section below.