I had never seen one of these before today. They’re great. Way better than reaching for a single pole in a crowded car and wrapping your hand around some stranger’s fingers. And If you have the whole thing to yourself you can hook your arm through it.
Which is pretty rare for a commuter train system with tracks that are often underground or raised above road traffic.
Especially since I think this is in the Denver airport where the trains are all computer controlled and going in a loop
E: ah I was wrong, but the comment still applies to the ones in Denver