---
product_id: 2215214
title: "First Alert 9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack"
brand: "first alert"
price: "₨74680"
currency: LKR
in_stock: true
reviews_count: 8
category: "First Alert"
url: https://www.desertcart.lk/products/2215214-first-alert-9120b-smoke-detector-hardwired-alarm-with-battery-backup
store_origin: LK
region: Sri Lanka
---

# Battery backup ensures protection during power outages Interconnects with other alarms for whole-home alert Ionization sensor for fast flaming fire detection First Alert 9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack

**Brand:** first alert
**Price:** ₨74680
**Availability:** ✅ In Stock

## Summary

> 🔥 Stay ahead of danger with the most trusted 6-pack smoke alarm set!

## Quick Answers

- **What is this?** First Alert 9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack by first alert
- **How much does it cost?** ₨74680 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.lk](https://www.desertcart.lk/products/2215214-first-alert-9120b-smoke-detector-hardwired-alarm-with-battery-backup)

## Best For

- first alert enthusiasts

## Why This Product

- Trusted first alert brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Uninterrupted Safety:** Battery backup keeps you protected even during power failures
- • **Smart Alarm Management:** One-button test/silence with latching indicator to identify the triggered unit
- • **Effortless Installation:** Universal mounting & tamper-resistant brackets speed up setup on any job site
- • **Whole-Home Connectivity:** Link multiple alarms so every corner of your home sounds the alert
- • **Fast Flaming Fire Detection:** Ionization sensor catches smoke from rapid fires before it’s too late

## Overview

The First Alert 9120B 6-pack hardwired smoke detectors combine ionization sensing technology with a reliable 85dB alarm and battery backup to ensure continuous protection. Designed for easy installation and interconnectivity, these UL-tested alarms provide whole-home coverage and smart features like a latching alarm indicator and end-of-life signal, making them a must-have for millennial professionals prioritizing safety and peace of mind.

## Description

Product Description This 6 pack of First Alert hardwired smoke alarms includes a 9 volt battery backup that continues to protect you in the event of a power failure. The detector features an ionization sensor for detection of smoke and fast flaming fires, as well as a loud, 85 decibel alarm. One button silences any nuisance alarms, and also tests detector functions, while lights indicate if the alarm detects smoke. The latching alarm indicator automatically identifies which unit initiated the alarm, even after the conditions that set off the alarm have subsided. And an end of life signal enhances your safety by letting you know when it's time to replace the unit. Connect it to compatible BRK or First Alert alarms within a single family residence. When one alarm is triggered, all connected alarms will sound. From the Manufacturer NOTE:The product is a hardwired alarm, also confirm if the wiring polarity is correct and that all wire nut connections are secure. A loose neutral (white wire) connection within the home junction box could prompt a device malfunction. First Alert 120 Volt Wire-In with Battery Backup smoke alarm in 6 pack contractor pack

Review: Quality fire alarms - These fire alarms were very easy to install and work well.
Review: Nice and affordable - Easy to install with pre-installed electrical wiring.

## Features

- Note: A loose neutral (white wire) connection within the home junction box could prompt a device malfunction
- 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 standards. Emits T3 pattern
- Keep your family safe with this 6 pack of hardwired smoke alarms; the battery backup means constant monitoring, even if there's a power failure
- Faster turnarounds on job sites with the easy-to-install, most-trusted alarms in home safety. easy-to-access battery drawer that allows you to replace the battery without dismounting the alarm
- 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)

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B000KKHWLU |
| Alarm | Audible |
| Batteries | 2 AA batteries required. (included) |
| Batteries Included? | Yes |
| Batteries Required? | Yes |
| Battery Cell Type | Zinc Carbon |
| Best Sellers Rank | #3,041 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #15 in Smoke Detectors & Fire Alarms |
| Brand | First Alert |
| Color | White |
| Customer Reviews | 4.7 4.7 out of 5 stars (11,579) |
| Date First Available | January 1, 2008 |
| Global Trade Identification Number | 00029054121134, 10029054121131 |
| Included Components | First Alert 9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack |
| Is Discontinued By Manufacturer | No |
| Item Package Quantity | 1 |
| Item Weight | 3.5 pounds |
| Item model number | 9120B6CP |
| Manufacturer | First Alert |
| Material | Plastic |
| Number of Items | 6 |
| Operating Humidity | 10-95% RH |
| Part Number | 9120B6CP |
| Pattern | 9120B6CP |
| Power Source | Battery Powered |
| Product Dimensions | 1.9"D x 5.6"W x 5.6"H |
| Sensor Type | Ionization |
| Size | 6-Pack |
| Style | Standard Detection |
| UPC | 111012470009 029054121134 |
| Voltage | 120 Volts |
| Warranty Description | 10 year |

## Product Details

- **Alarm:** Audible
- **Brand:** First Alert
- **Color:** White
- **Global Trade Identification Number:** 00029054121134, 10029054121131
- **Material:** Plastic
- **Operating Humidity:** 10-95% RH
- **Power Source:** Battery Powered
- **Product Dimensions:** 1.9"D x 5.6"W x 5.6"H
- **Sensor Type:** Ionization
- **Style:** Standard Detection

## Images

![First Alert 9120B Smoke Detector, Hardwired Alarm with Battery Backup, 6-Pack - Image 1](https://m.media-amazon.com/images/I/61gdjob8zBL.jpg)

## Questions & Answers

**Q: How do you silence this alarm? Apparently the low battery notification only starts after midnight and WILL NOT STOP unless you have another battery.**
A: I am certain this applies to all brand and model of smoke detectors.  Once the low battery beep starts happening, which is always just as your falling off to sleep, there is only one way to stop it.  Follow the steps outlined below.
1 - put all weapons in your house under lock and key. (this is for the safety of you your family and the manufacturer of the smoke detectors).
2 - Give the key to someone you can trust and that your are not capable of overpowering.
3 - Find the smoke detector that is beeping. Tip, its never the one you are standing beneath look up at.
4 - Ice your foot because by now you have kicked several walls, doors and furniture.
5 - Assuming you have located the guilty smoke detector and have not yet burned down your home or found a way to access your weapons in step 1, move to step 6.
6 - Take the guilty smoke detector(s) into the garage and smash them into as many pieces as possible with the biggest hammer you own.
7 - Most likely you have stopped the regular beeping but every 20 to 40 minutes or so you will still hear a beep.
8 - Start a fire in the back yard fire pit and when the fire has reached white hot with glowing red hot coals put the smashed bits and pieces into the fire and let it burn until it burns out on its own.
9 - Take a shower and get dressed because by this time your late for work and haven't slept.
10 - When you get home that evening and hear another beep burn the house but make it look like an accident.

**Q: Can a  BRK Model 92120B smoke detector directly plug in and replace an old BRK Model 4120B smoke detector (without an adapter)**
A: Yes.  I just replaced 2 very old (older than 10 years) BRK Electronics Model 4120B smoke detectors with these newer First Alert/BRK Brand Model 9120B units.  My older units were yellowed with age, so I also replaced the plastic base.  I did reuse the 3 pin electrical connector, as the "old" electrical connector matches the new unit.  The new smoke detectors are functioning/self-testing normally.

**Q: can these be connected together so if one is set off they  all go off?**
A: Have these in my home. House was built about 4 years ago (2017) Came with the house.. One goes off they all go off. They are connected to each other by wire. I did have the one in my bedroom that I had to replace prematurely.  It was just going off for no reason setting the entire house alarms. It was easily identified by the light on it that it was the culprit. Basic troubleshooting taking out of system all was good. I am a 42 year volunteer firefighter,  held a Chief, Captain , Luitenant, Firefighter and other various positions . My opinion,  having them all wired together, so when one goes off they all do is SMART! Been to multiple house fires through all my years and seen where the families on the first floor watching TV while their second floor or basement is burning up. 🔥

**Q: My entire home is equipped with BRK smoke detector (4120 B) and Carbon Monox Det (CO50120B). They need replacing. Will new BRK fit extant casings?**
A: The mount screws will fit but the base plate itself is slightly smaller and you might have to touch up paint. The connectors will fit as well so no need to change those

## Customer Reviews

### ⭐⭐⭐⭐⭐ Quality fire alarms
*by M***C on December 14, 2025*

These fire alarms were very easy to install and work well.

### ⭐⭐⭐⭐⭐ Nice and affordable
*by J***D on November 16, 2025*

Easy to install with pre-installed electrical wiring.

### ⭐⭐⭐⭐⭐ Very easy to install
*by C***S on January 24, 2026*

Smoke alarms have a 10 year life span I purchased these to replace existing devices and they work perfectly,

## Frequently Bought Together

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*Product available on Desertcart Sri Lanka*
*Store origin: LK*
*Last updated: 2026-03-01*