The thread size of 6AN :9/16-18 UNF. -6AN Flare 90 Degree -6AN Fitting Male Union BLACK reusable fitting.other sizes available. Size:6AN 90° Degree. Material: T6061 billet aluminum. 1.One-piece, CNC-machined T6061 billet aluminum design ensures the most direct path for unrestricted and redirected flow.