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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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$21.99
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Arrives Thursday, Nov 5
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At a glance

Condition
New
Model
9120B
Dimensions
5.6"D x 5.6"W x 2.2"H
Weight
22.68 g
Color
White
Style
9120BFF
Power Source
Battery Powered

Features 8

  • 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

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

Specs 21

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 22.68 g
Alarm Audible
Operating Humidity 10-95% RH

Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Thursday, Nov 5

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

This model, 9210BFF, is the First Alert model 9120B, but not in consumer packaging
Review Image by Jonathan B.
I needed to replace a First Alert model 9120B: it started to chirp because the battery was low. When I removed it from the ceiling I saw that it was over ten years old. I read that smoke detectors should be replaced at that age. I wanted an identical replacement so it would fit on the same mounting bracket in my ceiling and use the same power connector that's connected to AC power in the ceiling. I saw this model, 9120BFF, and the photos on the Amazon page show the unit labelled 9120B despite the "FF" at the end of the model number in the product description. I wasn't sure if it was the same, so I tried searching for model 9120BFF, but all I found was the same page on Amazon. But I ordered it anyway, and it is indeed the First Alert model 9120B. It is an exact replacement and works great. It fits on the same mounting bracket and uses the same power connector that my old smoke detector used. It comes with a new mounting bracket and power connector, which I don't need. And it comes with a new 9V battery: there's a plastic tab covering the battery terminals so no power is drawn until you pull the tab out of the unit when you install it. So why is this called model 9120BFF instead of 9120B? I think it's the packaging: see the picture attached. It comes in a plain corrugated box, which I assume is how they sell it to contractors. It's not in consumer packaging with a glossy cover like you'd find in a retail hardware store. But it's the same product: the label on the unit says Model 9120B, and it comes with instructions for that model. There's one other clue that it is sold to contractors: it includes a plastic dust cover that looks like a miniature shower cap. The dust cover is to be used during construction to keep dust out of the unit; you remove it when construction is finished. (It could be that the dust cover is also in the consumer version; I'm just guessing here.) Anyway, I'm happy with the purchase: it didn't require any ceiling work to replace my old smoke detector, which was my goal. ... show more
Reviewed in the United States on May 5, 2024 by Jonathan B.
Great price and worked w/ my existing units.
Review Image by Ike & Mary Pleasant
I got this to replace a smoke detector, which was acting up and this worked perfect. The price was great. Installation was easy. Connected simply. Works great. Matches the one I was replacing. Piece of cake! Noise/alarm is loud. Peace of mind is back. Pleased w this replacement.
Reviewed in the United States on July 24, 2026 by Ike & Mary Pleasant
Great product
Exact one that I was replacing. Simply plug and play. Worked perfectly.
Reviewed in the United States on September 13, 2026 by Vince F Pittsburgh PA
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
Amazing product
This product was so incredibly easy to install with zero tools needed aside from a ladder. It came with everything needed, and was as easy as connecting to the electric wires and twisting it to secure to the ceiling.
Reviewed in the United States on October 2, 2026 by Lex
Read carefully how to install.
This smoke alarm has a 10-year lifespan but after I ordered them I read horror stories of stale supplies being sold. The lifespan is not from the time of installation. It is from the date of manufacturing. So they could ship stale ones from a couple years ago and still be okay. These were ordered in September and made in June 2026. They all worked perfectly. They all fit the old brackets. When installing, shut off power to the unit; be sure to remove the plastic tab to activate the battery, and then turn the power back on. This will eliminate beeping from the unit self-programming that it is missing a battery if you turn power on and then remove plastic tab to activate battery. ... show more
Reviewed in the United States on September 26, 2026 by Jane
Well made unit.
This is a well made smoke detector. We bought one to replace the original smoke detector from when the house was built. The old one was chirping like tweety bird at 3am, and wouldn’t stop. My husband has no handyman skills so he took a hammer to it until it died. He installed this unit when received and it was easy to install. We ordered 2 more to replace the others before they start chirping. ... show more
Reviewed in the United States on September 23, 2026 by RoseL
Thankful for the right fit!
Doing what it is supposed to do. My 30 year old ones (4) died at the same time. Wasn't sure I would be able to find the right fit. Yes to Amazon and quick delivery.
Reviewed in the United States on September 11, 2026 by A. Thomas
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