This special aluminum adapter fitting has a male 6AN end (9/16-18 threads, 37° convex flare) to help adapt your fuel injection system to AN plumbing. The female 16x1.5mm metric end seals by an O-ring (not included) in the base of the female port. Black anodized aluminum, sold individually.
This type of fitting is often called a "bump tube" type. The matching male fitting has a tip that looks like our AN to Metric O-Ring Adapter Fittings, PArt No. 3497-007.