First Alert SMICO100-AC Interconnect Hardwire Combination Smoke & Carbon Monoxide Alarm with Battery Backup - 3 Pack
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Availability:
In Stock.
Arrives
Wednesday, Jul 1
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Size: 3-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
Features
- 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
- 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.
Brand: First Alert
Style: Precision Detection
Power Source: Corded Electric
Color: White
Item Weight: 1.68 Pounds
Alarm: Smoke, CO
Sensor Type: Ionization
Unit Count: 3.0 Count
Number of Items: 3
Manufacturer: Resideo
Power Source: Corded Electric
Alarm: Smoke, CO
Sensor Type: Ionization
Product Style: Precision Detection
Color: White
Item Weight: 1.68 Pounds
Brand: First Alert
Model Number: SMICO100-AC
Number of Items: 3
Manufacturer: Resideo
UPC: 029054022769
Mfr Part Number: SMICO100-AC
Unit Count: 3.0 Count
Item Type Name: Combination Alarm
Built-In Media: Easy Adapter Plug, 9V Battery
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Wednesday, Jul 1
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Similar Products
Top Amazon Reviews
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 Reviewed in the United States on October 21, 2025 by BlackMantis
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
Fortunately, I hope I never have to rely on these in an emergency, but it's reassuring to have them installed. First Alert has a long-standing reputation for reliability, and these detectors were easy to install and integrate into my existing system. The combination smoke and carbon monoxide protection provides added peace of mind for my home and family. A purchase you hope you never need, but one you're glad to have
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Reviewed in the United States on June 15, 2026 by Michael Collins
Size: 6-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
I ordered these to replace the discontinued 9120B model originally installed in my home during construction. In the ten years since then I’ve experienced zero issues so I trust the brand. They arrived quickly and the install was effortless. I was pleasantly surprised they came with 9v batteries pre-installed. They are priced at a premium but safety is paramount and I find they are of worth the money.
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Reviewed in the United States on June 3, 2026 by Alexander
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
Needed to replace our pair of wired 9-year old Ring-brand CO/Smoke alarms after one failed and began incredibly irritating beeping. Too bad, the Ring units were cool and nice looking until not, and no longer on the market. The First Alert units were highly rated and moderately priced. Simple to install - you just need to attach the plug with wirenuts. No wi-fi setup made it much less time-consuming. They are kinda ugly, so minus one star. But probably the best value/quality available.
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Reviewed in the United States on June 8, 2026 by J. Tenser
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
We recently installed the First Alert Combination Smoke & Carbon Monoxide Alarm, Interconnect Hardwire Detector, and we are extremely pleased with the decision. This unit is an outstanding choice for anyone looking to upgrade their home safety system, combining two essential protections into one convenient device. Top Features We Appreciated Dual Protection for Ultimate Peace of Mind: The biggest win here is having both smoke and carbon monoxide (CO) monitoring in a single unit. It gives great peace of mind knowing that the home is covered for two of the most critical household threats. It simplifies maintenance and ensures comprehensive safety. Seamless System Integration: A major selling point for us was its compatibility with our existing setup. This First Alert detector fit perfectly into our previous interconnected system (hardwired). The installation was straightforward, and it immediately linked up with the other alarms in the house, ensuring that if one goes off, they all do. This interconnectivity is vital for alerting everyone, no matter where they are in the house. Reliable Brand: First Alert is a name synonymous with home safety, and the quality of the unit feels robust and reliable. Conclusion If you are looking to replace old, separate smoke and CO alarms, or if you simply need to upgrade to a hardwired, interconnected system, this combination alarm is a superb choice. It delivers on its promise of simplifying safety while maximizing protection. Highly recommended!
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Reviewed in the United States on December 12, 2025 by Richard Fletcher
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
This is said to be a drop-in replacement for the older version, it is but requires the replacement of the plastic ring attached to the ceiling as well. Not so much fun when a high ceiling mounting is involved. Teetering on a 10 foot ladder and using both hands to replace the ring is less than fun. That said the unit came with a new battery and did not require electrical work, it just plugs in to the existing connector.
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Reviewed in the United States on June 3, 2026 by pberguy
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
Replaced 7 year old combo First Alert detector. Replaced ceiling ring, as is a different size than original. Electrical connection from original fit new. Overall easy installation
Reviewed in the United States on June 10, 2026 by CALABAMA
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMICO100-AC
This is the model recommended at the First Alert web site as a direct replacement for the First Alert model SC9120B. As others have mentioned, this one doesn't fit the mounting bracket for the SC9120B, so you'll have to remove the previous bracket and install the one that comes with this unit. For me, this wasn't a big deal and only required loosening two screws. The power connector is the same, so no electrical wiring changes are needed. I'm only giving four stars because they say it will last 10 years, but my home was built less than 14 years ago and I'm already starting to replace some for the second time, after they failed with the MALFUNCTION or END OF LIFE signal after only 6-8 years.
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Reviewed in the United States on April 19, 2026 by Michael Coren