These special aluminum adapter fittings all have one male 6AN end (9/16-18 threads, 37° convex flare) to help adapt your fuel injection system to AN plumbing. The metric end seals by an O-ring (included) at the tip of the fitting. Black anodized aluminum, sold individually.
Note that the hex is too small to seal by a crush washer or O-ring under the hex. The metric side of the fitting requires a special seat in the female port to seal at the O-ring at the tip.