A straight AN4 to M12*1.25 adapter, built to let a -4 AN hose end connect to a metric-threaded port. M12*1.25 turns up regularly on Japanese and European fuel rails, oil feed housings and sender bosses, and adapting it properly is far safer than forcing an imperial fitting into it. The AN4 end seals metal-to-metal on its 37-degree flare and needs no sealant; the metric end relies on the sealing washer or O-ring arrangement designed for that port, so fit it accordingly. AN4 is the right size for turbo oil feeds, pressure gauge lines and other low-volume circuits where line size is not the flow restriction.