An AN10 tee that puts male 37° flares on the straight run and a female swivel on the side branch. The swivel means the branch hose can be clocked into position without loading the tee or twisting the line, which is far easier to live with than a fixed female port. In AN10 it is used for splitting a fuel feed to twin rails, joining two returns into a single line, teeing off a cooler circuit or picking up a pressure sender or gauge line from a main run. Support the tee properly — a hose hanging off three ports puts real load on whichever component it is threaded into.