A friend stopped by to show me his garage sale purchase. We were both curious what the swivel part that is held by a screw detailed in the second photo was for or held. Saw lots of pictures online but no explanation.34245CB6-1EEC-4E10-B660-585684856C8E.jpgAA97E4B3-0964-43E7-9E67-7C6BAA39E28B.jpg