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

To be replaced every ten years according to the instructions. The old one is from April 2011 - so it's already started squeaking about a replacement. Industrial fair. But this unit is difficult to install because the bottom foam pad is too large all the way around (3/16 inch) and interferes with the locking mechanism. If you're fiddling with it on the kitchen table it can be handled, but if you're up a 10ft ladder. very difficult to align and repair. I ended up having to cut the gasket with an Olfa utility blade. No smart design!