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Non-returnable. Transportation of this item is subject to hazardous materials regulation
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Availability:
In Stock.
Arrives
Thursday, Nov 5
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At a glance
- Condition
- New
- Size
- 1-Pack
- Style
- Precision Detection
- Pattern
- SMICO100-AC
- Dimensions
- 5.5"D x 2"W x 5.5"H
- Weight
- 8.96 oz
- Color
- White
Features 5
- First Alerts 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
- Quick Connect Plug allows for easy installation with no need to rewire
- Battery backup provides continuous protection during power outages
- Test/silence button for efficient testing to ensure alarm is working properly
Description
The SMICO100-AC Interconnect Hardwire 2-in-1 Smoke & CO Alarm with Battery Backup utilizes First Alert's Precision Detection technology and meets new industry standards. Easily install and interconnect multiple alarms together to create an alarm system throughout your home.
Specs 20
| Brand | First Alert |
|---|---|
| Style | Precision Detection |
| Power Source | Corded Electric |
| Color | White |
| Product Dimensions | 5.5"D x 2"W x 5.5"H |
| Item Weight | 8.96 ounces |
| Alarm | Smoke, CO |
| Operating Humidity | 10-95% RH |
| Sensor Type | Ionization |
| Unit Count | 1 Count |
| Model Number | SMICO100-AC |
| Number of Items | 1 |
| Item Highlight | SMICO100-AC, 9V Battery Backup |
| Manufacturer | Resideo |
| UPC | 029054022752 |
| Built-In Media | Easy Adapter Plug, 9V Battery |
| Item Type Name | Combination Alarm |
| Mfr Part Number | SMICO100-AC |
| Product Style | Precision Detection |
| Item Dimensions D x W x H | 5.5"D x 2"W x 5.5"H |
No specs match.
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Thursday, Nov 5
This item is non-returnable:
Non-returnable. Transportation of this item is subject to hazardous materials regulation
View our full returns policy here.
Non-returnable. Transportation of this item is subject to hazardous materials regulation
View our full returns policy here.
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Similar Products
Top Amazon Reviews
Reliable & Reputable Detectors!
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
I have been a master electrician for 32+ years. If you're not 100% sure of what you're doing, hire a professional! Ok a lot of people are complaining about the new connector. It literally takes 60 seconds to rewire. I rewire anyways so I can put a meter on the ceiling wires to make sure everything is as it should be. The base is a tad smaller than my previous ones. They were from a different company though. It presented zero issues during the installation. I have 3 detectors upstairs and one in the basement. I wired them all and they all worked inline perfectly. When one goes off, they all go off. The alarm is very loud and high pitched. It also tests both the smoke and CO² detectors when pushing the test button. You'll get a beep and then another beep. Then it repeats. Meaning they are all working. Bonus each detector comes with a pre installed Duracell 9 volt battery. You also receive a dust cover for the detector if you need to work in that room. Kicking up dust or debris can get inside the unit and fault it. Nice little freebie to have. Although I didn't need, they come with very detailed instructions with diagrams. After I installed them all I tested it my way using certain techniques to get both detectors to alert. They passed on both smoke and CO². For this price point, I am very happy with these units. It gives me a sense of security knowing my family is protected. Please mark the back of your detectors with the date you install them. I use a black marker. Also be sure you were shipped the correct units. It should say on the outside label Combination Smoke/Carbon Monoxide Alarm. I've posted pictures along with a video. I hope this aids with your decision whether these are for your home or not. I will update again if I have any issues in the future. As of now they are working as they should and I again, am very happy with my purchase.
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Reviewed in the United States on October 21, 2025 by BlackMantis
Great plug and play option
Size: 6-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
We purchased these to replace our existing aged smoke detectors. They plugged right in and fit in the same bracket as the originals. I love that the green light indicates that they are working and if one goes off, it turns red. The others will all sound, but you know which one is activated by the color of the light.
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Reviewed in the United States on August 28, 2026 by Kathy Williams
Clear instructions, zero false alarms, and perfect for our new home!
Size: 6-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
We recently bought a new home and made it a top priority to replace all the old, outdated alarms for our family's safety. This 6-pack of First Alert units was the perfect solution to upgrade the whole house at once. Because these are hardwired, we had an electrician handle the installation to ensure the interconnected communication lines were wired safely and correctly. As you can see from my photo, it looks very clean mounted on the ceiling and has a solid green indicator light showing it has power. The precision sensors are excellent because we haven't had a single false alarm from kitchen cooking smoke since putting them up. It gives us total peace of mind knowing that if one alarm triggers, they will all go off throughout the house. If you are moving into a new place and want a reliable, high-quality safety system, this 6-pack is absolutely worth the investment.
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Reviewed in the United States on September 19, 2026 by Dou💋
They work - but why the bezel insanity?!?
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
It's great having both of these in one unit, and getting rid of wall-outlet-hogging monoxide detectors separately. These click right into most modern homes with hardwired detectors and are good to go. The only frustration (and this is just MADDENINGLY STUPID) - these First Alert alarms all come with bezels that seem scientifically engineered to be smaller than the one you're replacing. The screws line up great, everything else is plug and play, but EVERY installation means you'll have a 1/16 to 1/4 inch gap showing your old ceiling paint. WHY?!?!? Like replacing a ceiling fan beauty ring, these should all be made the EXACT diameter as all the old ones we're replacing by the thousands, if not a bit larger. There would be zero downside, and zero frustration. First Alert, most of us don't have touch-up paint, and your old brackets also don't fit the new alarms. It's killing me that this isn't a more voiced customer complaint, it's fractions of an inch of plastic. It's literally the only "thing" to deal with when replacing these. First Alert, PLEASE expand the outer diameter of this bezel where it meets the ceiling by a 1/4 inch?
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Reviewed in the United States on March 24, 2026 by Drew S.
Reliable and important for home fire, smoke, and CO-2 safety.
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
Fairly easy replacement install after replacement of mounting rings from previous older design models. New units are part of in-home, linked, hard-wired network and all are working flawlessly. Replacement of units in whole network (eight of them) are needed after about 12 years due to decay in nuclear chip used in the detector component.
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Reviewed in the United States on September 3, 2026 by G. Steele
BUYER BEWARE if you are replacing an SC9120B — CHECK THE SIZE AND RETURN POLICY FIRST
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
This was my first attempt at replacing my existing First Alert/BRK SC9120B alarms. I purchased two SMICO100-AC alarms for $48.50 each, plus tax, because this model was presented as the replacement for the SC9120B. Unfortunately, it was not a practical replacement in my home. The SMICO100-AC is physically larger and did not fit my existing installation the way the SC9120B did. Installing them properly would require additional work and potentially hiring a handyman. They are also noticeably bulkier and, in my opinion, much less attractive on the ceiling. I thought I had researched the replacement carefully. When a product is presented as the replacement for an existing model, I expected a much closer match in size and installation. Then I tried to return them. That is when I discovered they were non-returnable. So I was left with nearly $100 worth of brand-new alarms I could not reasonably use and no way to send them back. That is information buyers need to know before ordering. Smoke and carbon monoxide alarms are expensive. If a replacement is physically different enough that it may require additional installation work, both the size difference and the return restrictions should be extremely obvious before purchase. This is also unnecessarily wasteful. I now own two perfectly new alarms I do not want and cannot reasonably use simply because they were the wrong physical replacement. BUYER BEWARE: If you currently have an SC9120B, do not assume the SMICO100-AC will be a simple drop-in replacement. Check the exact dimensions, mounting area, wiring compatibility and return policy before ordering.
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Reviewed in the United States on October 1, 2026 by Book Lover
Cheaper alternative to NEST.
Size: 6-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
From Nest to this. I miss my old Nest Smoke Detectors, but 10 years went by fast. These are basic, simple, no wifi and no voice alerts, no walkway light but are bright in the dark room. Replaced the battery with Lithium 9v over the basic Duracell. Easy to replace. I dont get why others are not able to replace that battery? I dislike that beep in the background. Coming from NEST products it was nice I did not have to get an app to use these things. I do miss the spanish voice alerts and the hallway ring light when people walked by. This does not have that. The important thing is these were more cheaper, well made and should be good for the next decade.
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Reviewed in the United States on September 7, 2026 by Amazon Customer
A Great Replacement for the SC9120B
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
I purchased the First Alert SMICO100-AC Hardwire Combination Smoke & Carbon Monoxide Alarm to replace a discontinued First Alert SC9120B that was failing, and it has been a very good choice. I still have two SC9120B alarms in other parts of the house, and the SMICO100-AC integrated with the existing system without any issues. The only extra step was replacing the mounting base, but that was surprisingly easy and took about five minutes. For anyone looking to replace a discontinued SC9120B, the SMICO100-AC has been a straightforward, compatible replacement in my experience. The installation was quick, and having it work seamlessly alongside my existing First Alert alarms made the switch much easier than I expected. Overall, I’m very pleased with the purchase and would buy it again.
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Reviewed in the United States on September 24, 2026 by Mandy