This straight adapter mates an AN6 37-degree male flare to an M12*1.25 male metric thread. M12*1.25 is the fine metric pitch, distinct from the more common M12*1.50, and the two are not interchangeable, so identify your port before ordering. It is regularly found on Japanese and European fuel rails, oil feed housings and sender bosses. Paired with -6 AN hose it suits fuel feed and return lines, oil supply circuits and other moderate-volume plumbing where -6 is the standard hose size. The AN flare seals metal-to-metal and takes no sealant; the metric end depends on the sealing washer or O-ring specified for that port rather than on thread tape.