This straight adapter puts an AN10 37-degree male flare opposite an M20*1.5 male metric thread. M20*1.5 is a large port commonly used for oil filter housings, cooler adapter plates, oil pump take-offs and heavier sender bosses on metric engines. Paired with -10 AN hose it gives a generous, low-restriction path, which is exactly what oil cooler and dry sump circuits want. Because the metric thread here is comfortably larger than the AN side, the -10 flare is the limiting bore, so size your hose run accordingly. Fit the metric end with the sealing washer or O-ring specified for that port and torque the AN flare dry.