$47.99
Holiday Deal
· 6% off
was $50.97
Buy Now, Pay Later
As low as
$8.00
/ mo
Learn more
- – 6-month term
- – No impact on credit to apply
- – Instant approval decision
- – Secure and straightforward checkout
Ready to go? Add this product to your cart and select a plan during checkout.
Payment plans are offered through our trusted finance partners Klarna, Affirm, Afterpay, Zip, Apple Pay, and Google Pay. No-credit-needed leasing options through Acima may also be available at checkout.
Learn more about financing & leasing here.
Selected Option
Free shipping on this product
Extended holiday returns
Returnable until Jan 31, 2027 Learn more
Returnable until Jan 31, 2027 Learn more
This item's return window has been extended for the holiday season: Returnable until Jan 31, 2027
To qualify for a full refund, items must be returned in their original, unused condition. If an item is returned in a used, damaged, or materially different state, you may be granted a partial refund.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
Availability:
In Stock.
Arrives
Tuesday, Nov 17
At a glance
- Condition
- New
- Number of Items
- 3
- Model
- SMI100
- Dimensions
- 5.6"D x 5.6"W x 1.9"H
- Weight
- 9.6 oz
- Color
- White
- Style
- Precision Detection
Features 6
- 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
- Battery-operated alarm allows for easy installation and maintenance
- Front access battery compartment makes for easy battery replacements
- End-of-life warning lets you know when its time to replace the alarm
- Test/silence button for efficient testing to ensure alarm is working properly
- The date shown on the product is the Manufacture Date, which identifies when the product was produced
Description
The First Alert SMI100 Battery-Operated Smoke Alarm is equipped with First Alert's Precision Detection advanced sensing technology and meets new industry standards. This battery-operated smoke alarm is easy to install and the front access battery compartment makes for easy battery replacements.
Specs 19
| Brand | First Alert |
|---|---|
| Style | Precision Detection |
| Power Source | Battery Powered |
| Color | White |
| Product Dimensions | 5.6"D x 5.6"W x 1.9"H |
| Item Weight | 9.6 ounces |
| Alarm | Smoke Alarm |
| Sensor Type | Ionization |
| Unit Count | 3 Count |
| Number of Items | 3 |
| Model Number | SMI100 |
| Item Highlight | SMI100, 3-Pack |
| Manufacturer | Resideo |
| UPC | 029054022417 |
| Built-In Media | 9V Alkaline Battery |
| Item Type Name | Smoke Alarm |
| Mfr Part Number | SMI100 |
| Product Style | Precision Detection |
| Item Dimensions D x W x H | 5.6"D x 5.6"W x 1.9"H |
No specs match.
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Tuesday, Nov 17
Yes, absolutely! This item's return window has been extended for the holiday season: Returnable until Jan 31, 2027.
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.
- Klarna Financing
- Affirm Pay in 4
- Affirm Financing
- Afterpay Financing
- Zip Pay in 4
- Financing through Apple Pay
- Financing through Google Pay
Learn more about financing & leasing here.
Similar Products
Top Amazon Reviews
Affordable and Easy to Install
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMI100
This First Alert smoke alarm is a great basic option if you want something affordable and straightforward. Installation was quick and easy, and we had it up and working without any hassle. It feels like a good choice for adding or replacing a smoke alarm without spending a lot. Simple, practical, and does exactly what we needed.
...
show more
Reviewed in the United States on October 5, 2026 by Tricia Goss
smoke alarm
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMI100
This smoke alarm was just what I needed. It work's great in my RV, fit's perfect, very easy to install, the alarm was load so people can hear it. Price was good for this product
Reviewed in the United States on September 7, 2026 by connie k
I Really Like this Item
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMI100
I will try to be as honest as possible because I depend on other people's reviews and feel I want to help the best I can: Arrived as described. Well packed in a strong box. So easy I didn't even look at the instructions. It was replacing a detector that after 40 years had started beeping even with a new battery. I took down the old ring and this new ring covered all the mess of the old one plus I was able to use the holes from the old one even though it was a different brand. I did use the new screws because they were Phillips head and my old detector was so old it had used slotted screws. With the ring installed, I pulled the plastic tab that kept the battery from touching the terminals keeping the battery new until sold. The detector beeped and then after a pause gave two long beeps. Because I did not read the instructions, I wondered why, But after turning the detector onto the mounting ring I pressed the TEST button and it did same sequence of a quick beep, a pause and two long beeps. I figure that is it's test pattern. It is a perfect replacement and upgrade to what I had before and was compatible to the old one. At the price on Amazon I found it a good smoke detection value for the money. Best feature is the battery has a side compartment so you do not even need to remove the detector to replace the battery. I recommend. Good Luck.
...
show more
Reviewed in the United States on May 1, 2026 by Rowdy Ron
Simple to Install & Gives Peace of Mind
Size: 2-Pack
Style: Precision Detection
Pattern Name: SMI100
This smoke alarm was quick and easy to install, and it provides exactly what I was looking for-reliable protection and peace of mind. The instructions were clear, and it was up and running in just a few minutes. The alarm has a clean, low-profile design that blends in nicely with the ceiling. I also like that it's battery operated, so it continues working even if the power goes out. The test button is easy to access, and the alarm is loud enough to be heard throughout the house, which is exactly what you want in an emergency. If you're replacing an old smoke detector or adding extra protection to your home, this is a dependable, easy-to-install option from a trusted brand. Highly recommend!
...
show more
Reviewed in the United States on July 26, 2026 by Rachel
Good device, highly sensitive
Size: 2-Pack
Style: Precision Detection
Pattern Name: SMI100
If placing anywhere near kitchen (mine is maybe 12 feet from stove), the alarm is hyper sensitive and goes off at the slightest hint of heat (e.g., an air fryer will set it off). There's a button that can pause the beep but sometimes that only suppresses for a minute or two. Will have to relocate it (the old one never had this issue in current location). Bought 5 of these, easy to install and nice smaller size. Still recommend overall, just be mindful of the kitchen placement.
...
show more
Reviewed in the United States on September 26, 2026 by Alfred Limone
Brilliant nuisance-alarm reduction and incredibly easy battery maintenance!
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMI100
If you are looking to replace an outdated or constantly chirping detector with a reliable, standalone safety device, the First Alert SMI100 Battery-Operated Smoke Alarm is an outstanding upgrade. The defining feature of this model is First Alert's Precision Detection advanced sensing technology, which is specifically engineered to meet strict modern UL 217 industry standards. This smart ionization framework is highly sophisticated—it can distinguish between real, high-velocity fire emergencies and common, non-threatening cooking smoke or shower steam. This means you can mount it near kitchens or hallways without dealing with annoying false alarms every time you sear a steak or open a hot oven. Maintenance on this unit is exceptionally user-friendly. It features a front-loading battery compartment, which means you can swap out the backup battery in seconds without having to twist the entire detector off its ceiling bracket. It includes a multi-purpose Test & Silence button that lets you check the electronic circuits with a single tap, or temporarily mute a nuisance alarm for up to 8 hours. When the unit finally approaches the end of its operational lifecycle, an automated end-of-life chirping warning lets you know exactly when it is time to swap out the physical detector, ensuring your living space stays continuously protected.
...
show more
Reviewed in the United States on May 20, 2026 by Jeff S.
easy to install
Size: 1-Pack
Style: Precision Detection
Pattern Name: SMI100
perfect smoke alarm
Reviewed in the United States on October 19, 2026 by Ted
Fit our previous mounts! Big bonus.
Size: 2-Pack
Style: Precision Detection
Pattern Name: SMI100
Bought these as a replacement for hardwired smoke alarms that seem to randomly go off and then tell all the other smoke alarms to go off…always at night! These (amazingly) fit the existing mounts. The batteries came with very recent date stamps; and tested as “fully charged.” I’ll be replacing the remaining 2 as well. While these have gone up in price for something everyone should be able to afford; They are valuable to home safety. They “tested” fine. I hope I never have to learn about their reliability or smoke detection abilities.
...
show more
Reviewed in the United States on October 18, 2026 by Gr8OKcooks