A couple doors in the 1881 home where I work as a maintenance guy have these on them. They're installed vertically, and the handle pushes large deadbolts into both the top and bottom door frames of a single door in a set of double doors.
I spent the better part of my day fabricating replacement parts for one because I assumed it would be easier than trying to find them. And now, as I'm trying all my usual techniques to research it, and can't even find anything that looks like it, it seems I'm being proven right.
Google lens swears it's a plumbing fixture, and no combination of search terms I can think of is getting me anywhere in Google or in Bing. So now I'm using my third technique: asking the subreddit I think is most applicable. I'd like to try to find some parts, ultimately, but any information about these would be nice.
I'm off to my fourth technique, scouring Audel's builder's manuals :P Thanks in advance for any help!
Edit to add: I have a single video of the full thing, but no more pictures until morning.