WK723 filter.The flter element removes a small amount of solid particles in the liquid or air, which can protect the normal operation of the equipment or the cleanliness of the air. When the fluid enters the filter element with a certain filter screen, its impurities are blocked, and the clean fluid flows out through the filter element.Donaldson hydraulic oil filter P173737.Donaldson rotary hydrulic filter.Mann C23 440/3 paver air filter.