First Alert First Alert Brk Hardwired Smoke Detector + 1000 MPR Allergen Defense Filtrete Air Filter 4- pack
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Item #304190 |
Model #9120BP-12ST
Hardwired ionization smoke alarm with 9-volt battery back-up
Latching alarm indicator - remembers which unit initiated an alarm
Two silence features - can silence the low-battery chirp for up to eight hours or temporarily silence an unwanted nuisance alarm
Easy installation and maintenance
10-Year limited warranty
Tested to meet UL standards
General | |||
|---|---|---|---|
Color/Finish Family | White | Package Quantity | 1 |
Series Name | 9120 | Battery Type | 9-volt |
Sub-Brand | BRK | Package Contents | Alarm, 9-volt battery, adaptor plug, manual |
Type | Smoke detector | Alarm Sensor Type | Ionization |
Power Source | Hardwired | ||
Dimensions | |||
|---|---|---|---|
Height (Inches) | 5.59 | Size | Standard |
Length (Inches) | 5.69 | Width (Inches) | 2.25 |
Features | |||
|---|---|---|---|
10-Year Battery | No | Light | No |
Battery Back-Up | Yes | Low-Pitch Tone | No |
Battery Included | Yes | Sealed Battery | No |
Front-Load Battery | Yes | Voice Alert | No |
Hub Required | No | Voice Assistant | No |
Hush Feature | Yes | Voltage | 120 |
Interconnection | No | ||
Compatibility | |||
|---|---|---|---|
App Compatibility | No | Works with Android | No |
Bluetooth Compatibility | No | Works with Apple HomeKit | No |
Smart Compatible | No | Works with iOS | No |
Wi-Fi Compatibility | No | For Use with RVs | No |
Warranty | |||
|---|---|---|---|
Warranty | 10-year limited | ||
Certifications | |||
|---|---|---|---|
CA Residents: Prop 65 Warning(s) | No | Safety Listing | UL safety listing |
Miscellaneous | |||
|---|---|---|---|
UNSPSC | 46191500 | ||
Ratings may include incentivized customer reviews.
What Customers Are Saying
The smoke detectors are generally easy to install and replace older units. Many customers find the installation process straightforward. The product is considered a good value, especially when purchased in a multi-pack. However, some customers have experienced issues such as false alarms, short battery life, and premature failure. A few reviewers noted that the instructions could be clearer and the product markings are difficult to read. Overall, the smoke detectors seem to work well for most customers, but there are some quality control and longevity concerns.
Customer review summary generated by AI, including incentivized reviews.Customer Sentiment
4 Out of 5 Good
Purchased five of these on May 1, 2024 and installed, replacing five originally installed in my home when built in 2007! It was time! However, one of these detectors started its annoying beeping in October 2025. I replaced the battery but that failed to silence it so I purchased a replacement and installed it in November 2025. I think I had a bad detector and am attempting to see if the manuafacturer will refund me per the warranty info.
Verified Purchaser
Terrible products from this company
Would never recommend this company. 1. Purchased 6 CO2+Smokes from them in 2022 (manufactured Sept 22). FOUR OF THEM failed within two years at 3am. 5 chirps = "end of life." They want $7 shipping PER DEVICE to replace them. I, being curious, dismantled one of the defective alarms. IT WAS COMPLETELY CLEAN. NOT A SINGLE BIT OF DUST IN IT or anywhere on the photoelectric sensor. It was just a piece of trash. 2. Decided to purchase the product on this page. ONE of them had a dead battery. Another...
From BRK Hardwired (with Battery Back-Up) Ionization Smoke detector 6 -Pack
Not sure if it's working with other smoke alarms
I installed five First Alert smoke alarms OK, then discovered that I needed six. I bought this one which is very close in appearance to the other five. A problem is that I can't read the raised print on the smoke alarms which I think tell what model it is, because it's white on white, small print, very hard to see. The instructions were nearly useless, giving lots of warnings and describing WHERE to install it, but saying very little about HOW to install it. I turned off the circuit breaker ...
Verified Purchaser
Hi Flash, thank you for your review of the BRK Hardwired Ionization Sensor Smoke Detector. We are sorry to hear about this and really appreciate your...

Out of date when purchased
Purchased in Oct. 2024. Installed shortly after. Within a few weeks, two of them have already had to have their battery replaced. Likely more will soon. Called First Alert. She had me check the manufacture date on the detector, which is Feb. 2023. So they were already a year and a half old when purchased, which I did not know at the time. She said that's why the battery is already needing replacement, and likely the others will as well. No mention from her for compensation for having to replace ...
From BRK Hardwired (with Battery Back-Up) Ionization Smoke detector 6 -Pack Verified Purchaser
Hi KK88, we are truly sorry to hear about this and apologize for the inconvenience. If you need assistance with your detectors, please feel free to c...

2 of six failed with repeated false alarms
I replaced 6 of our smoke detectors with these. After 2 years, two of the units have now failed with repeated false alarms. The first one started failing in the middle of the night, which is terrifying to say the least. After the same one triggered multiple times, I ended up replacing it. Now another unit started failing and causing repeated false alarms. The units were both clean with no evidence of dust buildup or insects, and in each case there was no smoke in the house and no one cooking or...
Hi Wakramer, we are sorry to hear about this and apologize for the inconvenience. We will be happy to provide recommendations to prevent nuisance ale...

Overly Sensitive Junk
Do you want to be alerted to a fire? Do you want to be alerted to a boiling pot of water 75 feet away from the nearest smoke detector? Do you want to be alerted if someone a mile down the road has a bonfire? Then the 9120B is the smoke detector for you! Pure and utter garbage that triggers constantly for no reason at all (yes, they are new date codes, yes they have been cleaned.)
Hi Ryan, we are sorry to hear about this. We will be happy to help troubleshooting and provide recommendations to prevent nuisance alerts. Please fee...

Happy with purchase
I wanted to have all matching smoke detectors and I needed four. I had to use a handyman and it took him less than 30 minutes so have them do other jobs to make it worthwhile. Change every 5 years to be safe
From BRK Hardwired (with Battery Back-Up) Ionization Smoke detector 6 -Pack Verified Purchaser
Not that easy to install
I replaced the same model, and used the original base and the same wire plug. I researched how, but wasn't strong enough to make it connect properly and had to call an electrician which I should not have had to do. I did not appreciate the additional cost.
Verified Purchaser
Hi Rise, we are sorry to hear about this. This is not what you should expect and we apologize for the inconvenience. - Maria

Great product, works great
Great product and works great. In addition, all of my smoke detectors in my house are the same! Sure was easy to order online and pickup at the store in the lockers!
From BRK Hardwired (with Battery Back-Up) Ionization Smoke detector 6 -Pack Verified Purchaser
Check inside the box
Electrical wires for 4 of the 6 detectors were not included. Batteries had an expiration date less than 2 years from date of purchase.
From BRK Hardwired (with Battery Back-Up) Ionization Smoke detector 6 -Pack Verified Purchaser
Hi Sheila, thank you for bringing this to our attention. If you are missing the wiring harness of your detectors, please feel free to contact First A...









Hi Justin, we sincerely apologize you experienced this with your units. We appreciate the feedback and will utilize your comments as we update our pr...