First Alert SMI100-AC, Hardwire Interconnect Smoke Alarm with Battery Backup, 1-Pack

I was able to replace 7 old Firex smoke detectors with these using an adapter. I had to buy the adapters separately on Amazon. These were very easy to replace. I just unscrewed the old screws (not all the way, just enough to take off old base plate). These base plates fit perfect on the existing screws, so just tighten then down. I attached the adapters to the existing wires and then to the new smoke detector, screwed the new detector onto base plate, pulled out battery pull tab, tested and good to go. I bought 12 detectors in June 2026 and they were all manufactured on May 15, 2026 so I had no issue with any being years old as others have said. All detectors tested good (loud alarm, interconnected with no issue) and have had no false alarms. Overall great purchase!

Easy to replace the Kidde. Looks new and modern and is very easy to install especially if you're familiar with wire nuts and have some at home. If not, they're cheap at your hardware store. Use orange color wire nuts for the wires leading to the smoke alarm. Watch YouTube video on how they work. Very simple.

Great value

I got this as a replacement for an older hardwired smoke alarm, and it was pretty straightforward to swap in. The included quick connect plug made the setup easier, and it fit nicely once mounted. I also like that it has battery backup, so it still gives some peace of mind during a power outage. One thing I appreciated is that it is made to reduce nuisance alarms from normal cooking smoke, which is honestly a big deal if your old detector was too sensitive. The test/silence button is easy to reach, and the alarm feels solid, not flimsy or cheap. It also has the interconnect feature, so compatible alarms in the house can sound together. This is not a fancy smart unit, but for a dependable hardwired smoke alarm, it does the job well. Price felt fair, install was easy, and overall it seems like a solid upgrade from older builder-grade detectors.

Beware of purchasing this item from NEW AGE CANADA (Ontario). I ordered three of these alarms -- the SMI100-AC after doing substantial research. The company did not send me he SMI100-AC model alarm -- they sent me and older model (that is priced on Amazon currently at $15.00 less.) Not only did they not ask me if I was ok with the substitution, they did not adjust the price. Instead the thought to pocket the additional $15.00. Additionally, when I complained that I did not get the product I ordered, although they sent me a return authorization, they declined to send a pre-paid authorization. In my conversations with them they insisted that the model they sent me was the same item. I sent them my research to show them they were wrong -- that the two smoke alarms were not the same. Instead of admitting the mistake and offering me the pre-paid return, they basically told me to take it up with Amazon. This is as close to a scam as I have every come buying from Amazon. Amazon themselves, however, were great. They told me they would reinburse me for the shipping charges and look into the business practices of this company. Until they do be careful buying from NEW AGE.