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First Alert

First Alert BRK SMI100-AC Hardwired Smoke Detector with Battery Backup, 6-Pack

Based on 1,332 reviews
Condition: New
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$93.26
Save $6.64 was $99.90

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Availability: In Stock.
Fulfilled by Amazon
Arrives Saturday, Oct 31
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At a glance

Condition
New
Model
9120B
Dimensions
2.2"D x 5.6"W x 5.6"H
Weight
9.6 oz
Color
White
Style
SM6W01
Power Source
Battery Powered
Works with
smoke alarms

Features 6

  • 6 pack of hardwired smoke alarms, includes battery backup for power outages
  • Tamper resistant locking pins, single button silence/test and loud 85Db alarm
  • 120-Volt AC power with 9-volt battery backup (included) to keep alarm functioning during power outage
  • Open mounting design for easy installation with side load battery compartment for quick replacement and interconnect able up to 18 units (12 smoke, 6 co/heat/relay)

Description

Introducing the revolutionary BRK 9120 series smoke alarms which have been redesigned from the ground up. They install faster, perform better, and are even smarter than before. All of these improvements help reduce nuisance alarms and save you time and money. BRK Electronics smoke alarms are designed to be easy to install, easy to maintain, and quality-engineered for years of virtually maintenance-free service. The 9120B AC-powered smoke alarm with battery backup includes these features: ionization sensor which helps detect fast flaming fires that consume combustible materials rapidly. 120-Volt AC inter-connectable (with maximum 18 compatible devices). the alarm can be interconnected with up to 12 other compatible smoke alarms and six compatible devices like bells, horns, repeaters and door closers. If one unit triggers an alarm, all smoke alarms in the series will sound. Power indicators show which unit in the series initiated the alarm. Latching alarm indicator which automatically identifies which unit initiated the alarm. Smart technology to reduce nuisance alarms. 9-Volt battery backup for peace of mind during power malfunction. Single test/silence button which both silences a non-threatening alarm or low battery warning and allows you to test the unit's functionality. Perfect mount system including a gasket less base for easy installation and new mounting bracket that keeps the alarm secure over a wide rotation range to allow for perfect alignment. Mounting bracket lock for tamper resistance. Dust cover to keep unit clean during construction. 10-Year limited.

Specs 20

Brand First Alert
Style SM6W01
Power Source Battery Powered
Color White
Product Dimensions 2.2"D x 5.6"W x 5.6"H
Item Weight 9.6 ounces
Alarm Audible
Operating Humidity 10-95% RH

Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Saturday, Oct 31

This item is non-returnable:

Non-returnable. Transportation of this item is subject to hazardous materials regulation

View our full returns policy here.

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Leasing options through Acima may also be available during checkout.

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Top Amazon Reviews

Can't beat this eal.
These smoke units were a great value. Easy to install with all the needed hardware. My old connectors fit perfectly into the new units. The mount lined up with my old screw holes. Home run!!
Reviewed in the United States on September 23, 2026 by Leonard Logsdon
Very happy, Great quality
Works great! Very happy with the purchase. Easy to install
Reviewed in the United States on August 3, 2026 by Steven Tortu
Great to Have the Whole House Covered
I bought this 6-pack because we needed to replace several of our smoke detectors at the same time, and getting them all together was really convenient. I like that they’re hardwired but also have battery backup, so there’s an extra layer of protection if the power goes out. The detectors have a simple, clean look and having six made it easy to get everything matched throughout the house. The only downside is that if you’re replacing existing detectors, you should pay attention to compatibility and the wiring setup before ordering. It’s also definitely more money upfront buying a 6-pack, but for us it made more sense than replacing them one at a time. Overall, I’m happy to have the peace of mind of having new detectors throughout the house, and the battery backup is an important feature for me. Definitely check your existing setup before buying so you know these will work for your home. ... show more
Reviewed in the United States on October 1, 2026 by Rachel
Easy Replacement for model 9120B
Great product and easier then you think to install. I did not have to rewire just unplug old detectors and the harness plug fits the new ones exactly. These are an exact replacement for my 10 year old model 9120B. I replaced 5 in less than an hour. 1. turned off breaker 2. removed old units and replaced with new units / activated the new batteries as I replaced. 3 Flipped Breaker back on and went to one unit and held test button down for a little while then all 5 started chirping that they were in sync. ... show more
Reviewed in the United States on September 19, 2026 by Lou
Perfect for replacing old Firex detectors -- just remember to get the adapters.
I replaced a bunch of old Firex detectors with these, along with the corresponding adapters. Very easy to install -- one downside is you don't get any screws or bolts so plan accordingly. Otherwise, they all worked and they even come with batteries.
Reviewed in the United States on July 26, 2026 by Liz W.
They work!
I'm actually impressed that the cheapo batteries that came in these lasted an entire year! One thing I wish was different is the amount of light these throw at night. As two of them are positioned over beds, bit annoying. Otherwise, no complaints!
Reviewed in the United States on July 15, 2026 by Sock Monkey Fan
Good value
Easy to install and great value for the money. I recommend purchasing these.
Reviewed in the United States on October 4, 2026 by Lisa Riojas
These work so well, you wonder if you should uninstall them
These work so well that in an 8 foot ceiling, in a kitchen, they like to let you know about all of your cooking. So much so, that you wonder if you should uninstall them. I’m not saying they’re naughty, they just let me know everything… a bit of tattle tales I should say. So yes, they are a bit sensitive, they’ve even alerted me to too much steam.. Overall, I’m happy. They let me know how they feel, and I’d rather than be overly sensitive, then not sensitive enough. ... show more
Reviewed in the United States on September 19, 2026 by CH
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