Had ordinary smoke detectors around the house, but with recent remodeling, we took advantage of open walls to install hard-wired/connected detectors, and wanted a CO specific unit for the kitchen area (gas stove), where you can't have a smoke detector near the kitchen, for obvious reasons -- to this day, I think of my childhood every time a restaurant claims they make [a recipe] just like mom does, and yet I never hear their smoke detectors going off, LOL. First, the hard wire plug used for First Alert is the same between their smoke, heat, and CO detectors, but the mounting basses are different sizes, to prevent accidentally swapping in an incorrect detector for a another. We learned this last part by putting all the mounts in a tool bag and installing them 'randomly' where each unit would go...easily corrected, but it does make sense for safety sake. Second, there are reviews about First Alert being bought out by, or partnering with, another company that raises the question of compatibility among some models within this product line, hence deliberately buying from Amazon for easy return if needed..I got lucky, all mine worked together just fine. Fit and finish was similar to the smokes, but agree with other reviews that the sticker on CO back is perplexingly oversized, disagree that it holds the unit securely into the base for ceiling mount, as we found the mounting lugs engaged the mounting ring solidly on their own. Personally, I think it was because the stickers were cut slightly larger than the backside of the detector, maybe they used same size circle decal as for their smokes, guess we'll never know... When first installed, it triggered all the other hardwired alarms to go off every several seconds, but unplugging this unit, removing battery, letting it power down completely and then plugging it in before installing battery seems to be the secret handshake for adding a CO-only to their alarm loop. Pressing the test button for a few seconds to reset the capture light finalized the installation process. Haven't had any false CO triggers since. My biggest ding for this product? The same ding as published marketing for the other First Alert detectors: they say it can be installed with XX number of compatible units, but never give any information about which units are actually compatible with which. Why would a company brag about how many can be used, while making it hard for a customer to know which of the several alarm products sold under the First Alert name are or are not compatible with each other??? Based on reviews, some of FA's own hardwired alarms don't play well with others in the product line :( I say an update is needed on their website, at a minimum, to give the customer ease of mind by FA being upfront in compatibility, rather than leaving the customer questioning incompatibility when deciding which units to buy.
