First Alert SMI100-AC, Hardwire Interconnect Smoke Alarm with Battery Backup, 1-Pack
4.6 | 6,786 ratings
Price: 20.03
Last update: 02-03-2026
About this item
- First Alert's Precision Detection advanced sensing technology complies with new industry standards to reduce cooking nuisance alarms and provides early warning in the event of a home fire emergency.
- Through early warning interconnect, when one alarm sounds, all compatible alarms will sound
- Battery backup provides continuous protection during power outages
- Alarm indicator visually identifies the unit that initiated the alarm
- Quick Connect Plug included allows for easy installation with no need to rewire
Product information
Features & Specs
| Power Source | Battery Powered |
|---|---|
| Alarm | Smoke Alarm |
| Sensor Type | Ionization |
Style
| Product Style | Precision Detection |
|---|---|
| Color | White |
Measurements
| Item Dimensions D x W x H | 5.6"D x 5.6"W x 1"H |
|---|---|
| Item Weight | 0.6 Pounds |
Warranty & Support
Amazon.com Return Policy:Amazon.com Voluntary 30-Day Return Guarantee:You can return many items you have purchased within 30 days following delivery of the item to you. Our Voluntary 30-Day Return Guarantee does not affect your legal right of withdrawal in any way. You can find out more about the exceptions and conditionshere.
Product Warranty:For warranty information about this product, pleaseclick here
Feedback
First Alert SMI100-AC, Hardwire Interconnect Smoke Alarm with Battery Backup, 1-Pack
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Item details
| Brand | First Alert |
|---|---|
| Model Number | SMI100-AC |
| Global Trade Identification Number | 10029054022469 |
| Manufacturer | Resideo |
| UPC | 029054022462 |
| Item Type Name | Smoke Alarm |
| Built-In Media | Easy Adapter Plug, 9V Alkaline Battery |
| Unit Count | 1.0 Count |
| Best Sellers Rank |
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| ASIN | B0CJMN3443 |
| Customer Reviews | 4.64.6 out of 5 stars(6,776) 4.6 out of 5 stars |
Top reviews from the United States
- Beall WeismanGreat price , quick install, and great product!They look and work great the lights aren’t bright so sleeping isn’t a problem. Installation quick and easy for my Contractor.
No parts were missing although box was a litte dented which I am ok with. Great price!!!
Thanks Amazon. - Patrick LambertBest smoke detector!Ordered this set to replace all my upstairs smoke detectors! They were pretty much newer versions of what I had, very simple install all function well as well! Great value and great quality from a trusted brand!
- PatINCREDIBLE PRODUCT!!!!!!!!!!!Check this out!!! I ordered 3 of these to replace my 25 year old First Alert BRK 4120B I used when I build my home. To my absolute amazement this recommended replacement replaced exactly the ones I had that were 25 years old!!! The only issue was the original base was slightly different so I just put the new base on, plugged it in, and twisted it on. Took exactly 10 minutes to replace all three 25 year old smoke detectors.
Hats off to this company for making replacing these so easy. I thought this was going to be nightmare but so incredibly easy. Would recommend this to anyone trying to replace their old smoke detectors. Each unit also came with a battery backup. GREAT PRODUCT.....GREAT DESIGN !!!!!!!!!!!!!!!!!!! - iksherwaniGreat replacement smoke alarmsBrought these to replace 3 old yellowed ones. They were easy to install, I had to use wire nuts to tie in the new adapter . Inadvertently the alarms were tested to work when I turned on my gas fireplace but forgot to open the vent hood, that created some light smoke and triggered the detectors successfully so that was cool.
- MurphysLawReliable brandIt was time to replace my hardwired smoke detectors and while there are tons of brands with fancy features, I want reliability and a proven track record. I am not risking my family's safety on some discount smoke detector so I went with First Alert. I had Kidde smoke detectors previously so I had to replace the base and rewire them but it is a simple process that takes about 10 minutes for each detector from start to finish. They have only been installed a few days but they seem to work well. They include 9v batteries but be sure to check them as well as the date stamped on the back of the detector to make sure you are getting new products.
My only complaint about the smoke detector design is the pivoting tray used to hold the battery - 2 of 4 were very difficult to close and the plastic is very rigid and felt like it would snap. The marks for positive/negative can also be a bit hard to see. It is worth mentioning that the green power light is very bright. It doesn't bother me but could be an issue for some.
I recommend these detectors though I had a lot of issues ordering from Amazon. They do not sell 4 packs so I ordered a 3 pack and a single detector. I purposely ordered products that were shipped by Amazon but that is not what happened. The single detector was sent immediately from a 3rd party...not Amazon but whatever. It was 2 months old and seemed fine. I was informed the 3 pack of detectors was being sent by some other 3rd party and was delayed a couple of days. So Amazon just decided to use a 3rd party even though I actually paid more to get it shipped by Amazon. Then the delay was a week and it still didn't arrive and tracking showed it hadn't even been shipped. I cancelled the order and placed another making certain it was to be shipped from Amazon. Except it wasn't. Instead, it was shipped by another 3rd party and was delayed again, this time with no definitive delivery date. I had to cancel that order and went to Lowes where I paid more but at least I had them. Thankfully the single detector that was sent initially worked fine. I recommend the smoke detectors but I did not have a good experience ordering through Amazon. - BRUCE M BURKGreat replacement for 10 year old First Alert detectorsThese detectors were easy to install as a replacement for our previous First Alert detectors at the end of their 10 year life. The wiring unplugged and plugged back in, no problem. They rotated into the existing brackets. They even came with new backup 9v batteries. Just a press of the test button and they connected in.
- BobbyWorth the moneyDelivered on time. Installed them and they work great.
- Brett BordenEase of installation, easy to see test light.Easy, straightforward installation. Replaced a 25-year-old one-in-a-row system; it works as described for continued safety. Looks similar to the original. Has a replaceable battery for a long lifespan.