A large-step reducing adapter, threading into an AN16 male O-ring port and presenting an AN8 male 37-degree flare. AN16 bosses are found on dry sump tanks, big-capacity oil reservoirs, radiator and coolant fittings and fuel cell plates, and often only one modest branch line is needed from them. Rather than stacking two or three reducers, this does it in a single joint with fewer potential leak points. The port end seals on its O-ring against the machined face, so fit it without sealant. Note that the AN8 flare, not the AN16 port, sets the flow through this connection, so keep it off main supply circuits.