Best First Alert 9120B Smoke Detectors Updated February 2026
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Best First Alert 9120B Smoke Detectors
2026 Buyer's GuideUpdated February 2026
Advertiser disclosure About our rankings
Sort by:
Best Overall
Premium Pick
1

10.0

First Alert SC-9120B Hardwired Smoke and Carbon Monoxide Alarm with Battery Backup 2 Pack
Functionality
Ease of installation
Smoke detector quality
Value for money
Wiring
2K+ bought in past month
Best Overall
Premium Pick

10.0

1
First Alert SC-9120B Hardwired Smoke and Carbon Monoxide Alarm with Battery Backup 2 Pack
Functionality
Ease of installation
Smoke detector quality
Value for money
Wiring
2K+ bought in past month
Best Overall
Premium Pick

10.0

1
First Alert SC-9120B Hardwired Smoke and Carbon Monoxide Alarm with Battery Backup 2 Pack
Available in:  2 sizes
Functionality
Ease of installation
Smoke detector quality
Value for money
Wiring
2K+ bought in past month
2

9.9

First Alert Smoke Alarm, Interconnect Hardwire Detector with Battery Backup, SMI100-AC, 3-Pack
Ease of installation
Functionality
Smoke detector quality
Value for money
Replacement value
Fit
Save 30%

9.9

2
First Alert Smoke Alarm, Interconnect Hardwire Detector with Battery Backup, SMI100-AC, 3-Pack
Ease of installation
Functionality
Smoke detector quality
Value for money
Replacement value
Fit
Save 30%

9.9

2
First Alert Smoke Alarm, Interconnect Hardwire Detector with Battery Backup, SMI100-AC, 3-Pack
Available in:  2 styles ,  4 sizes ,  3 options
Ease of installation
Functionality
Smoke detector quality
Value for money
Replacement value
Fit
Save 30%
3

9.6

First Alert BRK 9120Bff-6 Hardwired Smoke Detector with Battery Backup, 6-Pack
Ease of installation
Functionality
Replacement value
Value for money
Compatibility
Resale value
Read Full Review
Save 17%

9.6

3
First Alert BRK 9120Bff-6 Hardwired Smoke Detector with Battery Backup, 6-Pack
Ease of installation
Functionality
Replacement value
Value for money
Compatibility
Resale value
Save 17%
Read Full Review

9.6

3
First Alert BRK 9120Bff-6 Hardwired Smoke Detector with Battery Backup, 6-Pack
Read Full Review
Ease of installation
Functionality
Replacement value
Value for money
Compatibility
Resale value
Save 17%
4

9.5

First Alert 9120B 120 Volt Hardwired Smoke Alarm With Battery Back Up 5 Pack
Quality
Ease of installation
Functionality
Value for money
Fit
Battery life

9.5

4
First Alert 9120B 120 Volt Hardwired Smoke Alarm With Battery Back Up 5 Pack
Quality
Ease of installation
Functionality
Value for money
Fit
Battery life

9.5

4
First Alert 9120B 120 Volt Hardwired Smoke Alarm With Battery Back Up 5 Pack
Quality
Ease of installation
Functionality
Value for money
Fit
Battery life
Best Value
Popular
5

9.3

First Alert Smoke Alarm, Battery-Operated Detector with Test & Silence Button, SMI100, 1-Pack
Smoke detector quality
Ease of installation
Value for money
Save 15%
Best Value
Popular

9.3

5
First Alert Smoke Alarm, Battery-Operated Detector with Test & Silence Button, SMI100, 1-Pack
Smoke detector quality
Ease of installation
Value for money
Save 15%
Best Value
Popular

9.3

5
First Alert Smoke Alarm, Battery-Operated Detector with Test & Silence Button, SMI100, 1-Pack
Available in:  3 sizes
Smoke detector quality
Ease of installation
Value for money
Save 15%
6

9.2

FIRST ALERT SC9120B Corded Electric Combination Alarm with Adapter Plugs for Easy Replacement
Ease of installation
Quality
Functionality

9.2

6
FIRST ALERT SC9120B Corded Electric Combination Alarm with Adapter Plugs for Easy Replacement
Ease of installation
Quality
Functionality

9.2

6
FIRST ALERT SC9120B Corded Electric Combination Alarm with Adapter Plugs for Easy Replacement
Available in:  2 styles
Ease of installation
Quality
Functionality
7

9.1

First Alert SMI100-AC, Hardwire Interconnect Smoke Alarm with Battery Backup, 1-Pack
Ease of installation
Functionality
Smoke detector quality
Value for money
Replacement value
Fit
Save 34%

9.1

7
First Alert SMI100-AC, Hardwire Interconnect Smoke Alarm with Battery Backup, 1-Pack
Ease of installation
Functionality
Smoke detector quality
Value for money
Replacement value
Fit
Save 34%

9.1

7
First Alert SMI100-AC, Hardwire Interconnect Smoke Alarm with Battery Backup, 1-Pack
Available in:  4 sizes ,  2 styles ,  3 options
Ease of installation
Functionality
Smoke detector quality
Value for money
Replacement value
Fit
Save 34%
8

8.9

First Alert BRK 9120B Hardwired Smoke Alarm with Battery Backup (3)
Quality
Functionality
Ease of installation
Value for money
Ease of replacement
Fit

8.9

8
First Alert BRK 9120B Hardwired Smoke Alarm with Battery Backup (3)
Quality
Functionality
Ease of installation
Value for money
Ease of replacement
Fit

8.9

8
First Alert BRK 9120B Hardwired Smoke Alarm with Battery Backup (3)
Quality
Functionality
Ease of installation
Value for money
Ease of replacement
Fit
9

8.8

First Alert 9120B Smoke Detector, Hardwired Alarm with Battery Backup, 3-Pack
Ease of installation
Functionality
Smoke detector quality
Value for money
Replacement value
Fit
Save 29%

8.8

9
First Alert 9120B Smoke Detector, Hardwired Alarm with Battery Backup, 3-Pack
Ease of installation
Functionality
Smoke detector quality
Value for money
Replacement value
Fit
Save 29%

8.8

9
First Alert 9120B Smoke Detector, Hardwired Alarm with Battery Backup, 3-Pack
Available in:  2 styles ,  4 sizes ,  3 options
Ease of installation
Functionality
Smoke detector quality
Value for money
Replacement value
Fit
Save 29%
10

8.5

First Alert SMICO110, 10-Year Battery Combination Smoke & Carbon Monoxide Alarm, 1-Pack
Smoke alarm quality
Ease of installation
Value for money
Save 10%

8.5

10
First Alert SMICO110, 10-Year Battery Combination Smoke & Carbon Monoxide Alarm, 1-Pack
Smoke alarm quality
Ease of installation
Value for money
Save 10%

8.5

10
First Alert SMICO110, 10-Year Battery Combination Smoke & Carbon Monoxide Alarm, 1-Pack
Smoke alarm quality
Ease of installation
Value for money
Save 10%

Our Top Choice

Best Overall
Premium Pick
1

10.0

First Alert SC-9120B Hardwired Smoke and Carbon Monoxide Alarm with Battery Backup 2 Pack
Functionality
Ease of installation
Smoke detector quality
Value for money
Wiring
2K+ bought in past month
Best Overall
Premium Pick

10.0

1
First Alert SC-9120B Hardwired Smoke and Carbon Monoxide Alarm with Battery Backup 2 Pack
Functionality
Ease of installation
Smoke detector quality
Value for money
Wiring
2K+ bought in past month
Best Overall
Premium Pick

10.0

1
First Alert SC-9120B Hardwired Smoke and Carbon Monoxide Alarm with Battery Backup 2 Pack
Available in:  2 sizes
Functionality
Ease of installation
Smoke detector quality
Value for money
Wiring
2K+ bought in past month
Related Categories
Hardwired Smoke DetectorHardwired Smoke AlarmFirst Alert Smoke AlarmHardwired Smoke DetectorFirst Alert Fire AlarmResidential Smoke Detector
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Related Categories
Hardwired Smoke DetectorHardwired Smoke AlarmFirst Alert Smoke AlarmHardwired Smoke DetectorFirst Alert Fire AlarmResidential Smoke Detector
Related Categories
Hardwired Smoke DetectorHardwired Smoke AlarmFirst Alert Smoke AlarmHardwired Smoke DetectorFirst Alert Fire AlarmResidential Smoke Detector