A straight female flare swivel adapter in AN4, sealing on the standard 37-degree AN flare seat. AN4 is the size you reach for on turbo oil feeds, gauge and sender lines, small fuel returns and clutch plumbing, and those runs almost always end up in cramped corners of the engine bay. The swivel joint means you can pull the fitting up tight and still rotate the line into the exact position you need, instead of backing off a torqued joint to get the routing right. Both ends take standard AN flare connections. Check that the components you are joining are genuine 37-degree AN flare rather than a 45-degree or ORB thread.