A same-size straight adapter with an AN6 male 37-degree flare on the hose side and an AN6 male O-ring port thread on the component side. AN6 is the workhorse size for EFI fuel feed and return, power steering and smaller oil cooler circuits, so this is one of the most-used adapters on any build. The straight port thread seals by squeezing its O-ring against the face of the boss, which gives a repeatable leak-free joint without sealant and without the over-tightening that tapered threads invite. Make sure the receiving port is a true O-ring boss; an AN6 ORB thread will not seal correctly in an NPT hole.