Can anybody identify this beam detector

Just looks like a plain black box to me: I’m not sure I’ve ever seen a duct detector that looks like that.

That is pretty much what everyone is saying. I have to replace about 40 sets. When i crack one open i will let you know if theres a name inside

That might help as I have no idea who might make this one.

Hard to tell from pic but it looks like an old Pyrotronics PB-2400 beam detector. I have a scanned manual for that thing. Here’s one for sale on eBay to help ID:

What kind of panel is it connected to?

That certainly looks like it!

I think you replied to the wrong person. I do believe Old fire alarm guy is correct though.