I bought some Model P1210 First Alert smoke detectors at Costco. The date on the back of the unit is 2018 Dec 08, which I assume is the date of manufacture. It started giving me the three-beep signal, which I can only assume is the low battery signal, on August 3, 2019. I checked everywhere and none of my other detectors are doing anything. I wasn't cooking. No smoke, but I doubt I can sleep tonight with this nonsense. 10 years, my foot!