A straight adapter putting an AN4 37-degree male flare opposite an M12*1.50 male metric thread. M12*1.50 is a widely used metric port on fuel rails, oil feed and drain bosses, sender locations and cooler plates, and this fitting converts one over to standard -4 AN braided hose. Take care not to confuse it with M12*1.25, which is a different fine-pitch thread and will not seal. The -4 AN size is chosen for turbo oil feeds, gauge and pressure sender lines, small returns and reference plumbing where flow demand is low. The AN flare seals metal-to-metal without sealant; the metric side seals on its washer or O-ring.