This reducing adapter presents an AN4 male 37-degree flare to your hose end and an AN8 male O-ring port thread to the component. It is the fitting to reach for when a housing, pump or regulator has a generously sized AN8 ORB boss but the circuit only calls for AN4 flow. Typical uses are oil pressure sender feeds, turbo oil supply lines and gauge plumbing teed off a large casting. The port seals on its O-ring against the machined boss face, so thread tape is unnecessary and the joint can be re-made without damage. Confirm the boss is O-ring port and not tapered pipe thread.