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BRK

BRK First Alert 9120BFF/ SMI100-AC Smoke Detector, Hardwired Alarm with Battery Backup, White, 1-Pack

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Arrives Friday, May 1
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Features

  • Keep your family safe with this hardwired smoke alarm the battery backup means constant monitoring, even if there's a power failure
  • Equipped with an ionization sensor, this smoke alarm reliably detects smoke from fast flaming fires and alerts you with an 85 decibel alarm
  • To ensure complete protection make sure to place one on each level of your home and in each bedroom
  • Can connect to other compatible BRK or first alert smoke detectors, to ensure all alarms will sound when smoke is detected
  • Simple to use, with a single test/silence button, and side load battery compartment tamper resistant locking brackets and universal mounting brackets make installation easy
  • Rigorously tested to meet UL standards120 volt AC power with 9V battery backup to keep alarm functioning during power outage
  • First Alert has been the most trusted brand in home safety since launching the first residential smoke alarm in 1958 (Based on a First Alert Brand Trust Survey in February 2018)
  • Faster turnarounds on job sites with the easy-to-install, most-trusted alarms in home safety

Description

Promote greater household safety with the First Alert 9120BFF Hardwired Smoke Alarm with Battery Backup. This 120 volt AC smoke detector uses an ionization smoke sensor to reliably detect smoke from hot, fast flaming fires and alerts you with a loud 85 decibel alarm. Designed to be wired directly into your home's electrical system, this hardwired smoke detector features a backup battery that helps keep the alarm functioning even in the event of a power outage. The gasket less mount helps ensure a perfect alignment for easy installation, while tamper resistant locking pins keep the alarm secure. And thanks to the convenient test/silence button, you can easily check whether the alarm is functioning properly and mute false alarms. This smoke alarm can integrate with up to 12 other First Alert or BRK hardwired alarms and features a latching indicator that identifies which unit triggered the alarm. 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 gasketless 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 warranty. All BRK Electronics smoke alarms meet UL 217 standard and are listed with the California State Fire Marshal. They use the new UL mandated repeating 85-decibel alarm horn pattern. 10-year limited warranty. This unit is approved for sale in Oregon after new revisions on law HB2586.--Bree NorlanderWhat's in the Box One smoke alarm, one 9-volt battery, and user's manual

Brand: BRK


Style: 9120BFF


Power Source: Battery Powered


Color: White


Product Dimensions: 5.6"D x 5.6"W x 2.2"H


Item Weight: 0.05 Pounds


Alarm: Audible


Operating Humidity: 10-95% RH


Sensor Type: Ionization


Global Trade Identification Number: 27


Power Source: Battery Powered


Alarm: Audible


Sensor Type: Ionization


Operating Humidity: 10-95% RH


Product Style: 9120BFF


Color: White


Item Dimensions D x W x H: 5.6"D x 5.6"W x 2.2"H


Item Weight: 0.05 Pounds


Brand: BRK


Model Number: 9120B


Global Trade Identification Number: 27


Manufacturer: First Alert


UPC: 029054015327


Item Type Name: Smoke Detector Alarm


Built-In Media: smoke detector, batteries, mount


Unit Count: 1.0 Count


Manufacturer Warranty Description: 10 Year Limited


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Friday, May 1

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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Top Amazon Reviews

    • Great alarm at a generic price!
It took me a long time to decide which smoke detectors to buy for my house, this model or the brand made by Kiddie. My house already had the Kiddie brand and this would mean a much faster replacement for all the smoke detectors in my house. Over time the Kiddie brand tended to chirp a lot and that drove everyone in the house crazy, especially my older and wonderful dog. My daughter said a candle lit in her room also set off all the smoke detectors in our house. If you go to the store you will find these labeled "BRK" with the words "First Alert" in smaller letters underneath and they come in a yellow and black box. It is unfortunate. Yellow and black packaging reminds me of generic food items back in the 70's and these items had a reputation for being below par. If I did not know what I was looking for I would have passed over these units in favor of something else, and I also noticed that BRK and First Alert puts their more expensive models in fancy and beautiful packaging. Thus, I fear that this company intentionally brands this "entry level" smoke detector in yellow and black to dissuade people from buying it and moving up to the more expensive models. I bought the contractor pack of this item as well as three single units to replace the nine smoke detectors in my house. All of these come with a free battery. I knew I would have to take down the old detectors, take down the mounts, and disconnect the old wiring in order that I be able to put in the new mounts and the new wiring for this smoke detector. It is a job that takes about 10 minutes at the most to completely swap out each of the units. Remember to shut off the circuit breaker! The alarm itself looks great. I like the design a lot better than the flat plastic orb. Once the new wiring harness is connected and the mount is secured to the ceiling, the new detectors snap easily into place for the wiring and you twist it onto the mount. The battery compartment is on the side and although the door for the battery looks cheap, all held up well and none broke. The alarm itself is easy to test, push the big button, and the alarm is loud enough to get anyone's attention. So far, cross our fingers, there have been no errant cheeps and no false alarms. Now to give Kiddie credit our old alarms were nearing the end of their expected lifespan so the new ones would have probably worked as well. I admit it, I went for the name brand! ... show more
Reviewed in the United States on July 27, 2015 by Scott Hansen
    • Excellent Replacement for Old Smoke Detectors
I researched various brands of smoke detectors and decided based on reviews and other factors (UL ratings) that the First Alert / BRK brand was the best and most reliable. I also read about ionization vs photoelectric sensors, and that many different websites recommend having a smoke detector that has both types of sensors installed in a single unit to alert to both types of common house fires (smoldering vs rapid flame combustion). I found the First Alert model smoke detector with both ionization and photoelectric sensors would not work in my application, as the combination sensor smoke detector is battery powered only. The smoke detector configuration in my home is hard wired. So I decided to purchase the First Alert Model SMI 100-AC, which has the ionization type sensor only, and is equipped to be hard wired and has 9 volt battery backup. The smoke detectors I was replacing were USI brand and the old pigtail was not compatible with the First Alert brand. So all 7 of my smoke detectors needed the new hire wire pigtail installed that comes with the First Alert detector. I found this job to be very easy and instructions for installation were very straightforward. Took me a total of about 2.5 hours to rewire all pigtails and install all 7 new detectors. I tested each new detector individually as each was installed, and then again as an interconnected series across the complete circuit. All worked perfectly and all are showing solid green LED, which indicates they are all receiving AC power and alarm and battery backup are working and active. The green LED light is very subtle and does not cast any light at all in a dark room that would be considered bothersome or glaring. Very happy with my choice and I highly recommend to anyone needing to install new smoke detectors or replace old ones that have reached end of life like mine. ... show more
Reviewed in the United States on March 22, 2025 by Michael F.
    • Big improvement over old one!
Product was delivered quickly and was very easy to install. Looks much better than the old one I replaced.
Reviewed in the United States on February 16, 2026 by Mark Lewis
    • Smoke Detector replaced easy
Review Image by Bill
I bought this as a replacement for one that was at end of life (Lasted 8 years). Easy to install and works great! I did not notice it was not carbon monoxide detector also. So make sure you check that if you want to monitor both smoke and Carbon Monoxide. Other then that, it fits on the same bracket as my old model SC9120B that is obsolete. Uses the same 120vac connector as the old. Interconnects with the my other 4 original monitors that still work. So if you have one that is NG, (my old one, chirped 3 times every 5 minutes or so even after cleaning and replacing battery) you can just replace that one and be OK. ... show more
Reviewed in the United States on November 10, 2025 by Bill
    • good detector, good price
This item was exact replacement for a 13 year old unit. Easy to connect
Reviewed in the United States on March 22, 2026 by unionhotel
    • Easy installation
Replaced my very old hard- wired smoke alarms . I’m a senior female and I was able to do the replacement myself. Very easy to do . Easy instructions . Peace of mind .
Reviewed in the United States on March 10, 2026 by A. BROSKY
    • Do Not Hesitate to Purchase
This is the second time I have ordered this smoke detector. They work perfectly and are a great deal.
Reviewed in the United States on March 16, 2026 by Pamela L Battenberg
    • Valid First Alert Replacement
This aftermarket replacement for my 10 yo "First Alert" smoke alarm used the same mounting bracket and electrical connector/plug as the original. Made for confidence in the replacement, which was quite easily performed.
Reviewed in the United States on February 12, 2026 by Able Ponder

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