The element is a valve which ejects out metered amount of oil to lubrication point. It is a sort of mini cylinder with a special check valve where stroke of piston determines the dosage of oil. The complete design of metering cartridge does not allow it to leak at low as well as at high pressure of oil. The ejected oil will not return back to the cartridge due to in-built check valve. The metering cartridges are supplied along with copper seal ring (washer).