Zinc and zinc-plated steel fittings have mild corrosion resistance. Zinc-plated brass fittings have good corrosion resistance. Fitting with a check valve prevents oil from leaking when pressure causes backward flow. The valve stays closed when not in use to keep out dirt and other contaminants. Fittings with a self-closing hinged cover block contaminants from entering equipment.

UNF and UNEF threads are similar to threads on a machine screw or bolt. They require a sealant, such as an O-ring, to minimize leakage.

Note: Fittings do not hold oil; any oil dispensed into the fittings passes into the part to be lubricated.