Review on FIRST ALERT BRK CO5120BN: Reliable Hardwired Carbon Monoxide (CO) Detector with Battery Backup in White by Eder Boesel

I had to replace 3 of these at the same time because one of them indicated end of life (5 beeps). Kit replaced 8 years ago. This time I followed the simple procedure in the manufacturer's video and it was easy. In my home, all smoke and carbon monoxide alarms are wired to a separate circuit protected by a 20 amp AFCI switch. Tools: ladder, screwdriver, eye protection. Turn off power at switch, remove alarm (unscrewed) from mounting plate, disconnect alarm cable. Plate unscrewed from the ceiling (2 Phillips screws loosened). I installed a new panel (the same 2 Philips). I connected the alarm cable, reinstalled (screwed) the new alarm. Pull out the plastic tab to activate the 9V battery. Press and hold the test button. Repeat for all CO alarms. Reset the AFCI circuit breaker. Check again, all 3 alarms will beep at the same time. DONE! Watch the manufacturer's video, it's definitely worth it.