I’ve found a bunch of those over the course of my homesearching timeline but still haven’t figured out what they are either lol. I’d thought I heard at one point that these are just some weird system smoke detectors rather than alarms though.
Oh, also…
Ultra-rare Fyrnetics thing
SmokeGard 907A2
What’s that? Not sure if it should go here because I don’t know if it’s smoke alarm or detector related
Dicon (fail as well)
?!
BRK equivalent of the 9120B (These are rarer than you might think!)
8201-301?