

Buy anything from 5,000+ international stores. One checkout price. No surprise fees. Join 2M+ shoppers on Desertcart.
Desertcart purchases this item on your behalf and handles shipping, customs, and support to Croatia.
🚨 Stay safe, stay smart—because your peace of mind deserves precision.
The First Alert SMI100 is a battery-operated smoke alarm featuring advanced Precision Detection technology that minimizes false alarms while providing early fire warnings. Its user-friendly design includes a front-access battery compartment, a test/silence button for easy maintenance, and an end-of-life alert to ensure continuous home safety. Ideal for quick installation and reliable protection, it’s a top-rated choice for modern households.











| ASIN | B0CJMP7WHH |
| Alarm | Smoke Alarm |
| Best Sellers Rank | #63 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #1 in Smoke Detectors & Fire Alarms |
| Brand | First Alert |
| Built-In Media | 9V Alkaline Battery |
| Color | White |
| Customer Reviews | 4.5 4.5 out of 5 stars (3,749) |
| Item Dimensions D x W x H | 5.4"D x 5.4"W x 1.9"H |
| Item Type Name | Smoke Alarm |
| Item Weight | 0.7 Pounds |
| Manufacturer | Resideo |
| Model Number | SMI100 |
| Operating Humidity | 10-95% RH |
| Power Source | Battery Powered |
| Product Style | Precision Detection |
| Sensor Type | Ionization |
| UPC | 029054022387 |
| Unit Count | 1.0 Count |
S**N
Reliable Smoke Alarm That Was Quick and Easy to Install
I recently purchased the First Alert SMI100 smoke alarms and I’m really happy with them. Installation was incredibly easy since they are battery operated, so there was no wiring needed. I had both alarms mounted in just a few minutes. The design is simple and clean, and the front battery compartment makes it easy to change the battery without taking the whole unit down. I also like the test/silence button on the front because it makes testing the alarm quick and simple. The alarm itself is loud enough that you would definitely hear it throughout the house, which is exactly what you want for safety. The detectors use updated sensing technology designed to give early warning of fires while reducing nuisance alarms from things like cooking smoke.Overall, these smoke alarms give me peace of mind knowing my home has reliable protection. They were affordable, easy to install, and work exactly as expected. I would definitely recommend them to anyone looking for a simple and dependable smoke alarm.
L**A
Excellent smoke detector
Excellent alarm, easy to install (I used double stick tape and it has held up perfectly). Thankfully I haven't tested it with smoke, but the test feature works great.
I**N
Will wake you and your kids if there is a fire
This First Alert smoke alarm is clearly the standard. Works reliably, is a powerhouse in a small size. It can be installed easily with a simple nail or screw without using the wall attachment materials included. It has a very loud piercing notification signal which is exactly what I needed to wake kids out of bed and get them started on how I have trained them if there is a fire. This unit was a replacement for a unit I have had for nearly 10 years. These smoke alarms are reliable.
C**Y
Works great, quality of the body is meh
A great, cheap option for a smoke detector! Installed onto the wall super easy. One issue, is the battery compartment can catch when trying to install the battery, but a little pressure and it clicks into place (without breaking any plastic, thankfully).
K**S
As described. Great quality.
These aren't interconnected, and are powered by battery only. But they do the job as described and are a lower cost option to replace the more costly interconnected "wired" models.
N**F
Replaced Exp First Alert Smoke Detectors w/New
I just installed these 2 First Alert smoke detectors, so I can’t give you a long time use review, but I’m happy with my purchase. These replaced two 10 year-old similar First Alert smoke detectors that had reached their expiration date. I was very pleased with those, which is why I looked for the same smoke detectors. I couldn’t find the exact same ones, so I replaced with these, which look similar and are basic like the first pair. Although the size of the new ones are a little bit smaller than the ones they replaced, I was pleased to find that the new brackets fit the 2 screws I already had in the walls from the old ones. I was concerned that I would be patching and drilling, but I didn’t have to, so installation was easy peezy. The other thing that is different on the new ones is that the batteries are 9 V versus the AAs for the old ones. I prefer AAs because it’s a battery that I always have around the house and they are easy to come by and inexpensive, relatively speaking. However, the new detectors came with batteries, so I don’t have to worry about replacing them for another year.
K**.
Does the job with only two screws.
Honestly, you don’t think about these until they’re chirping at 3 AM, but this one is a solid "set it and forget it" win. I picked it up because our old one was yellowing and looked like a relic from the 90s. Installation was a breeze—basically two screws and you’re done. It’s compact enough that it doesn’t look like a giant UFO on my ceiling, which is a plus for the aesthetic. I live in a pretty foggy part of the Bay Area and some detectors get weird with the humidity, but this one hasn’t given me a single false alarm even when the morning mist rolls in or I’m searing a steak in the kitchen.
P**Y
A most have a working smoke detector.
Got these for a new house. Easy to install. Dependable brand in our house works great if we get to mush smoke so got the same for my sons house.great value smoke detectors I am afraid if fire cause had ine when I was 3 in my closet. We did not have one 63 yrs ago and a cousin walked into my room and said saw smoke. Every room and garage has one.
Trustpilot
1 day ago
2 weeks ago