AN6 is the most-used size in performance fuel plumbing, and this 90° swivel adapter is one of the more useful fittings in the range. A male flare goes into the component or adapter, while the female swivel end rotates freely so the hose can be clocked to any angle before final tightening. That solves the common problem of a fuel rail, filter, regulator or pump outlet pointing the wrong way in a tight bay. It also works for oil, coolant and water plumbing. The 37° cone does the sealing, so a clean seat and a firm — not brutal — nip is all that is required.