I found this on my ceiling and I was wondering what it is.

A blurry photo of a white device shaped like a rounded square, with a small black outline of the same shape in the center of it. The device has a cluster of 7 holes near one corner.

  • 10
    Looks like a smoke alarm. What you mean you found it on your ceiling? Not something somebody would break in and put up. If a smoke alarm they are not life time, need to be replaced every so many years.
    – crip659
    Feb 13 at 1:35
  • 3
    Is this a rental apartment or do you own? If it is a rental, check with your neighbors to see if they have similar items and/or check with management. Could be: smoke alarm, CO alarm (less likely) or some sort of emergency announcement system (though more typically those are on the wall with obvious lights or??? Feb 13 at 1:47
  • 5
    Use a broom handle to push the large square button in the middle. Does this cause it to make a very loud noise? If so, it's probably a smoke detector. (If not, it's still probably a smoke detector, but the batteries and/or the entire unit need to be replaced.)
    – zwol
    Feb 14 at 14:41
  • 1
    @crip659 If someone had broken in to install it, then it would probably be a microphone and/or camera disguised as a smoke alarm. Feb 14 at 17:59
  • 2
    It looks suspect. Are we sure those holes aren't for microphones and you are probably under heavy surveillance. I am surprised that you found it. They should have installed it to match the ceiling color better. Rookie spies.
    – DMoore
    Feb 14 at 22:49

1 Answer 1


To me, it appears to be a First Alert AC10-500 smoke/CO alarm

enter image description here

Manufacturer link

P.S. First Alert may manufacture other alarms with a similar shape

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