A reducing straight adapter from the AN920 range, taking an AN4 male 37-degree flare out to an AN6 male O-ring port thread. Use it when the component has a larger tapped ORB boss than the line you actually need to run, which is common on regulators, fuel logs and filter housings that are cast with one generic port size. The straight thread and O-ring seal on the port face, so no sealant is required and the fitting can be clocked without affecting the seal. The AN4 side keeps flow modest, which is exactly what you want for gauge feeds, sender lines and turbo oil supply.