I just replaced my Kidde wired smoke detectors with these battery operated ones. Bought 2 to begin with, and just ordered 4 more for the rest of the house. Perfect fit! So easy to install. I just had to take off the old mount, install the new mounts, pull the battery tag, test and they are up and going. I have always went with Kidde, but have noticed over the years that some of their products aren’t as good as they used to be. The last batch of Kidde smoke alarms I bought on Amazon had a 2014 date, but I bought them in 2018. My now ex put them up. Not sure why he didn’t check the date. So I only got 7 years out of them. The First Alert smoke alarms are so easy to test. Just overall a good product.