Donaldson hydraulic oil filter P550251.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.Mann C23 440/3 paver air filter.BFU 700X filter.HU 947/1X filter.