Search  for anything...
BRK

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

  • Based on 18,317 reviews
Condition: New
Checking for product changes
$19.96 Why this price?

Buy Now, Pay Later

As low as $4 / mo
  • – 4-month term
  • – No impact on credit
  • – 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, PayTomorrow, Affirm, Afterpay, Apple Pay, and PayPal. No-credit-needed leasing options through Acima may also be available at checkout.

Learn more about financing & leasing here.

Free shipping on this product

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

View our full returns policy here.

Availability: In Stock.
Fulfilled by Amazon
Arrives Sunday, Jun 22
Order within 22 hours and 38 minutes
Available payment plans shown during checkout

Recently Viewed

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: First Alert


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


Sensor Type: Ionization


Global Trade Identification Number: 27


Number of Items: 1


Brand: ‎First Alert


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


Sensor Type: ‎Ionization


Global Trade Identification Number: ‎27


Number of Items: ‎1


Manufacturer: ‎First Alert


UPC: ‎029054015327


Part Number: ‎9120BFF


Item Weight: ‎0.8 ounces


Item model number: ‎9120B


Batteries: ‎1 9V batteries required. (included)


Is Discontinued By Manufacturer: ‎No


Size: ‎1-Pack


Pattern: ‎Filter


Voltage: ‎120 Volts


Item Package Quantity: ‎1


Number Of Pieces: ‎1


Type of Bulb: ‎LED


Cutting Diameter: ‎5.6 Inches


Included Components: ‎smoke detector, batteries, mount


Batteries Included?: ‎Yes


Batteries Required?: ‎Yes


Battery Cell Type: ‎Alkaline


Warranty Description: ‎10 Year Limited


Assembled Diameter: ‎5.6 Inches


Date First Available: June 1, 2006


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Sunday, Jun 22

This item is non-returnable:

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

View our full returns policy here.

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

Learn more about financing & leasing here.

Similar Products

Top Amazon Reviews

    • Replace Your Smoke Detectors after 8 to10 years!
Review Image by Sandy Springs Customer Sandy Springs Customer
My smoke detector and secure sensors all seem to have batteries go out in the middle of the night when I'm asleep. Two weeks ago the smoke detector went off with a low battery beep and nothing including Changing the battery would stop the beeps. After googling the brand i found out that after a max of 10 years the detector is no good and it will beep to let you know it needs replacement. I found this exact model on Amazon. It was an easy and quick replacement. It even came with a new battery. If your smoke detector have been around for awhile don't wait until they wake you up in the middle of the night. Start replacing them now! ... show more
Reviewed in the United States on June 6, 2025 by Sandy Springs Customer Sandy Springs Customer
    • 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.
    • Ease of integrating into your old system.
These smoke detectors are the exact replacement for our 20-year-old malfunctioning alarms. They are the same brand, and we only had to replace the base plate. The "pigtails" were also the exact same and included in the package, but we were able to use the original ones so it was easy to just replace the baseplate then plugin the pigtail and apply the new smoke alarm then test. All 4 alarms were then communicating when pushing the test button. Would recommend!! ... show more
Reviewed in the United States on May 28, 2025 by margaret marcellus
    • Tight pins
Very difficult to line up pins, very snug, hard to insert into prior female ending of electrical connection.
Reviewed in the United States on May 24, 2025 by gordon affleck
    • Delivered quickly and worked as advertised.
Item was delivered quickly and worked as advertised. It was not the lowest price, but it had the most complete description, so I knew it would fit in an existing mounting. I really like getting things right the first time with the right part.
Reviewed in the United States on June 5, 2025 by Michael Pettigrew
    • Quality product.
The right replacement for the original smoke alarm. When you test function, it activates smoke and carbon mono oxide alarm as well.
Reviewed in the United States on June 10, 2025 by EdSa
    • Wired smoke detector replacement.
The smoke detectors in my house are 20+ years old and malfunctioning. This unit works great as a replacement.
Reviewed in the United States on June 9, 2025 by Stephen R. Hall
    • inexpensive to buy.
had a handy man install this since it is a hardwire.
Reviewed in the United States on June 13, 2025 by Wayne K

Can't find a product?

Find it on Amazon first, then paste the link below.