First Alert Combination Smoke & Carbon Monoxide Detector White 3-Pack — Hardwired with Battery Backup

The First Alert BRK SC9120B-3 is a three-pack of hardwired combination smoke and carbon monoxide alarms with battery backup designed for continuous, interconnected home monitoring.

Combining ionization smoke sensing with an electrochemical CO detector, these BRK units provide dual-threat detection for both fast-burning fires and carbon monoxide leaks. Hardwired for permanent installation and engineered to interconnect with compatible First Alert/BRK devices, the SC9120B-3 keeps your home monitored even during power outages thanks to included battery backups. The white, low-profile design fits most ceilings and walls, and simple mounting, tamper-resistant brackets, and an easy-access battery compartment make upkeep straightforward.

How does this alarm detect both smoke and carbon monoxide?

The SC9120B-3 uses two separate sensing technologies: an ionization sensor for detecting small combustion particles typical of fast, flaming fires, and an electrochemical CO sensor that reads carbon monoxide concentration. When either sensor is triggered, the unit sounds an 85-decibel alarm and can signal other connected alarms for whole-home notification.

• Ionization chamber identifies fine particles from fast-burning sources.
• Electrochemical CO sensing measures toxic gas levels over time.
• Indicator lights show whether smoke or CO caused the alert.
• 85 dB alarm provides clear, audible warning for occupants.

What are the installation and power options for these alarms?

These detectors are hardwired into the home electrical system for reliable power and include a side-load battery compartment to provide backup during outages. Universal mounting brackets and tamper-resistant locking hardware simplify ceiling or wall placement, and the units are suitable for interconnection with other compatible BRK/First Alert alarms.

• Hardwired connection for continuous main power.
• Side-load battery compartment for emergency backup.
• Universal mounting brackets and locking features for secure installation.
• Interconnects with other compatible BRK/First Alert detectors.

How do I operate and maintain the SC9120B-3 alarms?

Operation centers on a single test/silence button that lets you verify functionality and temporarily silence nuisance alerts. Routine maintenance is minimal: replace batteries per the manufacturer’s recommendation, clean the exterior to prevent dust buildup, and follow local codes for testing frequency to keep sensors responsive.

• One-button test/silence for quick checks and temporary hush.
• Visible LED indicators for smoke and CO status on the faceplate.
• Dust cover and accessible battery compartment for easier upkeep.
• Manufacturer guidance suggests periodic testing and battery changes.

Why choose a 3-pack instead of single units?

Purchasing a three-pack helps ensure consistent protection across multiple rooms or floors, while simplifying installation with identical models that interconnect. Bundling units is often more cost-effective and guarantees uniform alarm behavior when one detector senses danger and triggers the rest.

• Three matched units keep multiple areas coordinated in an alert.
• Cost-saving compared with buying separate detectors individually.
• Easier planning for coverage across bedrooms, hallways, or levels.
• All units share the same mounting and wiring standards for consistency.

Who is this for: Homeowners, landlords, and renovators who want permanent, professional-grade protection across several rooms will appreciate the SC9120B-3. It’s well suited for families seeking combined smoke and CO detection with battery backup, for builders installing code-compliant safety systems, or for anyone replacing older single-function alarms with a single, interconnected solution.