I just moved into a new (to me) home. There are these two devices, one on the wall about a foot off the floor and another on the ceiling in the kitchen eating area. A small red light comes on behind the plate when there is a noise. What are they? Thanks. enter image description here enter image description here

  • Glass break sensor for an alarm system, perhaps?
    – BMitch
    Aug 26 '16 at 15:42
  • Do you have a security system?
    – bib
    Aug 26 '16 at 15:42
  • Can you unscrew and see what wires are running from the back?
    – Levi
    Aug 26 '16 at 15:45
  • 1
    There may be a name and model number on the back but it may be part of an alarm system as suggested above.
    – Ed Beal
    Aug 26 '16 at 15:49
  • Thanks for the quick comments. This site is great. Yes, I have an alarm. Glass break makes sense, they are in places that would be difficult to put motion detectors.
    – Merccooper
    Aug 26 '16 at 16:11

This is a Flush‑mount Glassbreak Detector. Here is a picture of another one that looks very similar made by Bosch.

Glass Break Detector

EDIT: Just realized @BMitch deserves credit for this as he posted the correct answer in a comment before I posted this answer.

  • 1
    Well, I don't know how @BMitch feels about it, but I for one don't get too riled up about someone else posting the right answer (particularly if they've gone and done some legwork) since after 25K there's nothing else to "get" but the bragging rights, and I don't brag much; plus Tester101 has the top spot pretty well tied up so long as I have a job to hold down, or any life outside of this site ;^) Have 10 points on me.
    – Ecnerwal
    Aug 27 '16 at 1:11
  • Yeah. They typically may light up on loud noises. I know of at least one model that lights up on a loud clap to confirm it is powered on and functional.
    – D-on
    Aug 27 '16 at 9:56

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