This straight adapter mates an AN10 37-degree male flare to a 3/4″ NPT male pipe thread. It is a step-up adapter: the -10 AN side is a big, free-flowing connection typically used for oil cooler lines, dry sump plumbing, high-volume fuel feeds and transmission cooler runs, while the 3/4″ NPT side threads into castings, pumps, filter housings and cooler bodies that were tapped in pipe thread. NPT is tapered and seals by wedging, so it needs a suitable thread sealant or PTFE tape wound in the correct direction, kept clear of the first thread. The AN flare needs nothing but a clean face and correct torque.