This adapter threads into an AN6 male O-ring port and presents an AN8 male 37-degree flare to the hose end. It is used where a component is only tapped AN6 but the rest of the circuit runs AN8, typically to keep one consistent hose size through a fuel or oil system rather than dropping down and back up again. Keep in mind the AN6 port remains the narrowest point, so the benefit is routing and hose-end commonality rather than extra flow. The O-ring seals on the boss face, so install it dry and tighten only enough to compress the seal squarely.