1/4 Pipe Thread
These fittings are also known as hydraulic grease fittings. Brass fittings are more corrosion resistant than zinc-plated steel fittings. Brass Fittings with a check valve prevent grease from leaking when pressure causes backward flow. The valve stays closed when not in use to keep out dirt and other contaminants. Please see below for our Quality American Made Hydraulic Grease Brass Fittings: