First Alert Smoke Alarm, Battery-Operated Detector with Test & Silence Button, SMI100, 1-Pack
4.5 | 23,052 ratings
Price: 16.99
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.
- 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 it’s time to replace the alarm
- Test/silence button for efficient testing to ensure alarm is working properly
Product information
Features & Specs
| Power Source | Battery Powered |
|---|---|
| Alarm | Smoke Alarm |
| Sensor Type | Ionization |
User guide
| Operating Humidity | 10-95% RH |
|---|
Style
| Product Style | Precision Detection |
|---|---|
| Color | White |
Measurements
| Item Dimensions D x W x H | 5.4"D x 5.4"W x 1.9"H |
|---|---|
| Item Weight | 11.2 ounces |
Warranty & Support
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First Alert Smoke Alarm, Battery-Operated Detector with Test & Silence Button, SMI100, 1-Pack
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Item details
| Brand | First Alert |
|---|---|
| Model Number | SMI100 |
| Manufacturer | Resideo |
| UPC | 029054022387 |
| Customer Reviews | 4.54.5 out of 5 stars(22,445) 4.5 out of 5 stars |
| Best Sellers Rank |
|
| ASIN | B0CJMP7WHH |
| Item Type Name | Smoke Alarm |
| Built-In Media | 9V Alkaline Battery |
| Item Height | 1.9 inches |
| Unit Count | 1.0 Count |
Top reviews from the United States
- Tiffany KingGreat, Long-Lasting Smoke Alarm Brand!I bought this as a replacement for a 10-year old First Alert Smoke alarm in my son's room. I was hoping it would just screw in to the existing bezel that comes with it but it is a lot different. So be prepared to remove and install the new one. I was able to use the same screw holes as the old one though, so it was nice to not have to make new holes in the wall. Seems to be a good quality, I had to jiggle the battery around to get it to engage. It is battery-operated so there is no wiring to mess around with and makes it easier to install. The alarm sound is loud (as it should be) and it doesn't chirp randomly like my other one started doing (even after the battery was changed). This is a great brand and my last one lasted over 10 years and I still have other First Alert Smoke Alarms in the house that I test and are still going strong after 10 years.
- kthompsoGood, reliable, and affordable. Better than AC detectors.I replaced all of my hard-wired smoke alarms with these battery-operated alarms. They work great. No more chirps that are difficult to track. I put a reminder on my cell calendar to change all the batteries every year and I've had no issues. The alarm is loud and easy to test while standing on the floor with a broom handle.
- terrySmall low profile; works, much nicer than larger unitsPetite little cuties that were the easiest install of any smoke detector ever. I had to replace all 6 in my house (they were 20 years old). The font in the instruction guide was micro, so I used a magnifying glass and the readability was fine. The are compatible with any room because their tiny size and profile keeps them un noticable. I tested each one before installing and they all function. The box came with all 6 smokes, all the needed screws, and 2 anchors of each smoke incase you need them. Very pleased
- RicGood alarmWorks as described. Loud as heck too.
Disappointed that I couldn't buy more than 3. I needed a total of 5 so I ordered 3 and then another 2. - RICHARD ALLEN RAGERQuality product.I have had First Alert hard wired smoke detectors in my home for the past 7 1/2 years. They work. I have never had a problem with them. I purchased this battery operated smoke detector because one of my hard wired smoke detectors is located 12 feet above a step in my stairway and will be very difficult to reach when the time comes that I need to replace it. I would rather spend a few dollars on a new battery operated smoke detector and spend the time installing it near the hard wired smoke detector than fall down a stairway and possibly kill myself. These First Alert smoke detectors are good products and are designed to save your life. So, whatever money you spend on them, it is money well spent.
- FallenRangerzEasy to install and takes less than 15 minutesGot tired of my incompetent maintenance team servicing my apartment. Always installed faulty smoke alarms that would beep after a day nonstop or at random times of the day with no smoke or issues. Installed this myself and it's hell of a lot easier than whatever brand they chose, it's more user friendly with an easy as pie way to swap out batteries without having to unmount the alarm. Best part though? It's been what, a month or more maybe since I've gotten it? Not a single unnecessary beep unless it ACTUALLY picks up on smoke. Its been quiet as a mouse and I no longer have to wake up in the middle of the night contemplating if it should eat a 9mm for breakfast. Very happy with this brand and this product and thank you for the beautiful sleep.
- SethPerfectThis First Alert smoke alarm is exactly what I needed — no complicated setup, just a dependable unit that gives peace of mind. It came with everything I needed, including the battery, and I had it mounted in under five minutes using the included hardware.
The test and silence button works perfectly, and it’s loud enough to hear from across the house. I also like that it has a low-battery chirp that’s noticeable but not obnoxious.
It’s lightweight, and the design is clean enough that it blends in well with the ceiling. I installed a few of these — one in the hallway and another in a bedroom — and both work exactly as expected.
Pro tip: write the installation date on the side with a Sharpie — that way you’ll remember when to replace it.
For the price, it’s hard to beat. Reliable protection from a trusted brand. - Margaret R. SimonEasy to install. Worked at once.Normal size, easy to install. Worked at once, as described. Very loud!