I am thrilled with the result. Simple to setup. I now have 5 smoke alarms and one combination CO2/smoke alarm made by Kidde that are all with wireless connections to each other. If the CO2 alarm occurs, it will say CO2 problem from all 6 alarms.
I was able to just remove the old smoke detectors and put these new Kidde detectors in the same places in minutes. Adding this last one was just as simple as installing the first 5. I tested them and they say Fire alternated with a loud alarm. The cost is good since it is so easy to install them.
I like the idea that the battery lasts 10 years which is the same amount of time that the alarms should be replaced. My old alarms were 22 years old and therefore no longer effective. I have now turned of the smoke detector circuit breaker since these all run on only battery.
No false alarms have occurred in since I installed the alarms 3 weeks ago.
Having a ten-year battery gives peace of mind, and having the ability to communicate with other devices via it's built-in Wi-Fi is especially attractive. Plus, I was able to replace an alarm in my kitchen that always gave nuisance warnings every time I opened the oven door.