First Alert SMI100 Battery Smoke Alarm
- Ionization sensor, smoke only
- 2 alarms per pack
- 9V alkaline battery included
- Battery powered, front access compartment
- 5.6 by 5.6 by 1.9 inches
- 9.6 ounces each, white
Last refreshed Sep 8, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
A simple twin pack of battery smoke alarms with an ionization sensor and a front access battery door. It senses smoke only, so it does not replace a carbon monoxide alarm.
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ASIN: B0CJLN45JZModel: SMI100Category: Smoke Detectors & Fire Alarms
Overview
A bedroom or hallway without wiring gets this battery operated First Alert ionization alarm, shipped as a pair with a nine volt alkaline battery. A front access compartment makes battery changes straightforward.
Its strength is easy installation with no electrician and quick battery swaps from the front. The limitation is that it relies on one battery and senses smoke only, with no listed carbon monoxide or interconnect feature.
Who it's for
Renters, small apartments and additional rooms are well served by a battery alarm that mounts without electrical work. Owners who need linked alarms across a larger house should look at an interconnected model.
Pros and cons
- No wiring needed
- Front access battery compartment
- Two alarms per pack
- Precision Detection sensing listed
- Smoke only, no carbon monoxide
- No interconnect listed
Performance notes
An ionization sensor responds best to fast flaming fires, and detection depends on a working battery, so regular checks matter. Nine volt power lets the unit run through a power cut, since it never relies on the house supply.
Specifications
| Brand | First Alert |
|---|---|
| Model | SMI100 |
| Dimensions & fit | |
| Item Dimensions D X W X H | 5.6 x 5.6 x 1.9 inches |
| Item weight | 9.6 ounces |
| Power & efficiency | |
| Power Source | Battery powered |
| Construction & materials | |
| Color | White |
| Included components | |
| Unit Count | 2 |
| Other details | |
| Sensor Type | Ionization |
| Alarm | Smoke |
| Product Style | Precision Detection |
| Builtin Media | 9V alkaline battery |
| Item Highlight | SMI100 |
Closest rivals on specs
Kidde 10SDR Compact Smoke Detector- Item Weight 0.6 vs 0.39 pounds (+54%)
Frequently asked questions
Does the First Alert SMI100 detect carbon monoxide?
No. The listing gives the alarm type as smoke with an ionization sensor. It is not a carbon monoxide alarm, so use a separate detector for that.
Is the SMI100 hardwired?
No. It is battery powered with a 9V alkaline battery built in.
How do I change the SMI100 battery?
The description says the front access battery compartment is made for easy battery replacement.