This is the swivel mechanism for the high pressure air at the center of my Campbell Hausfeld automatic retracting air hose reel. That hose is crimped directly on the swivel mechanism instead of adding negligible cost with a threaded fitting.
The upshot is that the hose is not replaceable by itself if damaged. And of course parts are not readily available. Throw out the whole thing instead and buy something new. Assholes.
The lesson is to never purchase that brand again for any product and to not replace it with anything that has the same planned obsolescence.