Okay, here’s a never-before-seen rare one, the Kidde/Nighthawk/Fyrnetics KN-COSM-I, the non-battery backup version which nobody here in the community owns whatsoever. Although the more well-known Canadian version (dash ICA) is more common than this but still very rare, thus a Canadian collector in the community owns one.
I predicted this alarm in my topic, Predict Undocumented Fire Alarm Variants! and 1 day after I look up on Google and AI does something good for once and linked me to a manuel of the dash IB/I, and on the title page and page 1 of the *.pdf file, I noticed this fine print:
Don’t know if anyone noticed this before in their dash IB manuels but this is exactly why you should
Point proven.