What's this?

Meter connection? It specifies flow direction.

Check valve, I would guess.

That was my first guess, but there are two caps that serve some purpose.

I don’t know. It could be a double, but they are usually copies of one another. Most check valves I’ve seen were mounted with the caps facing up. I was going to comment about it possibly being upside down but based on the orientation of the print that is obviously not the case.

Did you by chance get a close-up where the text in the triangle is legible? The “Type 135” didn’t provide much clue.

I believe Chuck is correct a “Double Check”.

No, this is the only photo from an old inspection.

http://www.watercorporation.com.au/home/builders-and-developers/building/backflow-prevention/how-to-install-a-backflow-devicecheck valves.png

I’d say that’s it, thanks Bob!

Does not appear it would matter if they face up or down.