First Alert 9120B 120 Volt Hardwired Smoke Alarm
With Battery Back Up 5 Pack
Price as of 2026-06-02. Check Amazon for the current price.
Quick Decision
Is This Right For You?
- •Buyers who prioritize quality over price in Smoke Detectors
- •Those who want a top-rated option — in the top 5% of Smoke Detectors by rating
- •First Alert loyalists — the brand spans 100 products in our database
- •You're on a tight budget — $6 above the category average of $77
- •First Alert SMI100 — 58% cheaper at $35 (Score A-)
📊 Based on data analysis of 37 products in this category.
Mubboo Score: B
How It Compares
This Product First Alert 9120B 120 Volt Hardwired Smoke Alarm | Most Popular First Alert SMI100 | Best Rated Kidde i4618AC Hardwire Smoke Alarm | Best Value Kidde Smoke Detector | |
|---|---|---|---|---|
| Price | $83.26 | $34.98 | $178.99 | $35.97 |
| Rating | 4.7/5 | 4.6/5 | 4.6/5 | 4.0/5 |
| Reviews | 411 | 4,421 | 1,532 | 1,256 |
| Mubboo Score | B | A- | B | B |
Quick Specs
- Alarm
- 85dB
- Color
- White
- Style
- 5 Units (9120B)
- Unit Count
- 5.0 Count
- Item Weight
- 0.01 Ounces
- Sensor Type
- Ionization
- Manufacturer
- First Alert
- Model Number
- 9120B
What People Say
Synthesized from 40 reviews · 100% verified purchases.
Test units upon arrival, as included batteries may be dead or drain quickly. Verify activation tab functions and note that sealed-battery models may not interconnect with other alarms.
- Ease of Installation
- Good Value
- Reliable Performance / No False Alarms
- Compatibility with Existing Mounts
- Long Battery Life / No Battery Changes
- Pre-installed Battery Drains Quickly
- Dead on Arrival / Activation Issues
- Flimsy Build Quality
- Confusing Instructions
Expert Picks in Smoke Detectors
- Kidde Smart Smoke Detector — Best smoke detector overall
- First Alert Battery Smart Smoke & Carbon Monoxide Alarm with Nest Protect — Best for Google Nest users
- Kidde Ring-Enabled Smart Smoke and Carbon Monoxide Detector — Best smoke detector for Alexa and Ring users
- First Alert SMI100 Dual Sensor Smoke Detector — Best budget smoke detector
Category recommendations from independent expert publications. Source links in References.
Related Video Reviews
Key Features
- ✦Imported
- ✦Tamper resistant locking pins, single button silence test and loud 85dB alarm
- ✦120-Volt AC power with 9-Volt battery backup (included) to keep alarm functioning during power outage
Source: product listing on Amazon.
About First Alert
- 100 products in our database
- Average rating: 4.6/5 across all products
- Price range: $13.98 – $648
- Categories: Carbon Monoxide Detectors, Fire Extinguishers, Smoke Detectors
Other Smoke Detectors
Bottom Line
First Alert 9120B 120 Volt Hardwired Smoke Alarm earns Mubboo Score B. Priced at $83 — a premium option, above the category average of $77. Rated 4.7/5 from 411+ reviews. Strong buy if: buyers who prioritize quality over price in smoke detectors, those who want a top-rated option. Skip if: you're on a tight budget — First Alert SMI100 (Score A-, $35) may fit better.
Frequently Asked Questions
Is the First Alert 9120B 120 Volt Hardwired Smoke Alarm worth buying in 2026?
It earns a Mubboo Score of B, with a 4.7/5 rating from 411 reviews — better than 95% of Smoke Detectors we track.
How much does the First Alert 9120B 120 Volt Hardwired Smoke Alarm cost?
It is currently $83.26 — premium-tier pricing for Smoke Detectors.
How does the 9120B 120 Volt Hardwired Smoke Alarm compare to other Smoke Detectors?
The category's most-reviewed alternative is the First Alert SMI100 (4.6/5, 4,421 reviews, $34.98). The 9120B 120 Volt Hardwired Smoke Alarm carries a Mubboo Score of B vs A-.
Sources & References
Mubboo may earn a commission from purchases made through links on this page. Prices and availability are accurate as of the last sync (2026-06-02) and may change.