Search  for anything...
First Alert

First Alert SMI100, Battery-Operated Smoke Alarm, 2-Pack

  • Based on 1,793 reviews
Condition: New
Checking for the best price...
$34.96 Why this price?
Save $0.01 was $34.97

Buy Now, Pay Later

As low as $8 / mo
  • – 4-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

FREE 30-day refund/replacement

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: Only 8 left in stock, order soon!
Fulfilled by Amazon
Arrives Aug 19 – Aug 20
Order within 10 hours and 11 minutes
Available payment plans shown during checkout
Protection Plan Protect Your Purchase
Checking for protection plans...

Recently Viewed

Size: 2-Pack


Style: Precision Detection


Pattern Name: SMI100


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
  • 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

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.

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


Sensor Type: Ionization


Unit Count: 2.0 Count


Number of Items: 2


Power Source: Battery Powered


Alarm: Smoke


Sensor Type: Ionization


Product Style: Precision Detection


Color: White


Item Dimensions D x W x H: 5.6"D x 5.6"W x 1.9"H


Item Weight: 9.6 ounces


Brand: First Alert


Model Number: SMI100


Number of Items: 2


Manufacturer: Resideo


UPC: 029054022400


Mfr Part Number: SMI100


Unit Count: 2.0 Count


Item Type Name: Smoke Alarm


Built-In Media: 9V Alkaline Battery


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Aug 19 – Aug 20

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.

  • Klarna Financing
  • Affirm Pay in 4
  • Affirm Financing
  • Afterpay Financing
  • Zip Pay in 4
  • Financing through Apple Pay
  • Financing through Google Pay
Leasing options through Acima may also be available during checkout.

Learn more about financing & leasing here.

Similar Products

Top Amazon Reviews

    • Worked well and easy to install and test.
Size: 3-Pack Style: Precision Detection Pattern Name: SMI100
My wife wanted these to replace the ones in her mom’s house. I installed them and they were easy to install and they came with batteries and were easy to test. The alarms are well made with strong materials. They are light and the sensitivity is good. Great replacement product. Worth the money
Reviewed in the United States on June 18, 2026 by Oscar
    • For the money a good product so far.
Size: 1-Pack Style: Precision Detection Pattern Name: SMI100
Installed easily. Works fine so far!
Reviewed in the United States on June 18, 2026 by G. A. Neal
    • Reliable Smoke Alarm That Was Quick and Easy to Install
Size: 2-Pack Style: Precision Detection Pattern Name: SMI100
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. ... show more
Reviewed in the United States on March 4, 2026 by Jean
    • Nice Alarm
Size: 1-Pack Style: Precision Detection Pattern Name: SMI100
Good cheaper alarm that works well
Reviewed in the United States on June 17, 2026 by D
    • Maybe works a little too well.
Size: 3-Pack Style: Precision Detection Pattern Name: SMI100
Easy to install and I love that it takes AA batteries. I will say it’s a bit too sensitive. Too much steam from the hair dryer will set it off. But, better safe than sorry, I guess.
Reviewed in the United States on June 11, 2026 by Kelsy
    • Pricey but works fine
Size: 1-Pack Style: Precision Detection Pattern Name: SMI100
These were a lot cheaper a few years ago. Easy to install even if you have to hard wire it. If you are replacing an old model, hard wiring is s must unless you purchase the connector sold separately
Reviewed in the United States on June 5, 2026 by EB
    • Great deal, easy replacement of old detectors
Size: 2-Pack Style: Precision Detection Pattern Name: SMI100
Great price, good quality , easy installation to replace our old hard wired smoke detectors.
Reviewed in the United States on May 29, 2026 by Bob M
    • Great product.
Size: 3-Pack Style: Precision Detection Pattern Name: SMI100
Performs as promised. Good product. Thankfully we haven't needed it to save our lives in a fire. I trust it would, though.
Reviewed in the United States on June 20, 2026 by Marketing Professor in Connecticut

Can't find a product?

Find it on Amazon first, then paste the link below.
Checking for best price...