First Alert hardwired ionization smoke detector 3-pack — 9120B with 9V battery backup, interconnectable

First Alert 9120B is a hardwired smoke alarm with ionization sensing and a 9V battery backup sold in a 3-pack for interconnected, continuous home monitoring.

This three-pack of First Alert (BRK 9120 series) hardwired smoke detectors combines fast-flame ionization sensing with smart nuisance-reduction features and a 9-volt battery backup so your home stays monitored even during power interruptions. Redesigned mounting hardware and a single test/silence button make installation and maintenance faster on job sites and in homes. The units interconnect so a single triggered alarm sounds all linked devices, and a latching indicator shows which unit started the alarm.

How does this smoke detector reduce false alarms and save time during installation?

The 9120B uses improved electronics and sensing to minimize nuisance alarms while retaining sensitivity to fast flaming fires. It also includes a gasketless base, a new mounting bracket, and a dust cover to speed up installation and protect the unit during construction.

• Smart nuisance-reduction technology lowers unnecessary alerts.
• Gasketless base and universal mounting bracket for quicker alignment.
• Dust cover protects the sensor during renovation or painting.
• Mounting bracket lock increases tamper resistance on finished installs.

What happens if power fails — will the alarm still work?

Yes — each 9120B contains a 9-volt battery backup so detection continues when AC power is interrupted. The unit emits low-battery warnings and includes a single test/silence button to verify operation and temporarily silence non-emergency alerts.

• 120V AC primary power with 9V battery backup for outages.
• Single test/silence button for quick functional checks.
• Side-load battery compartment for easy battery replacement.
• Low-battery chirp and silencing feature to reduce annoyance.

Can these alarms be interconnected across a house or job site?

They are fully interconnectable with compatible First Alert/BRK devices: when one alarm senses smoke it can trigger up to a network of other alarms and notification devices. Power indicators and a latching alarm flag identify which unit initiated the event.

• Interconnect up to 12 compatible smoke alarms and six compatible notification devices.
• Power indicators show the initiating unit in a triggered network.
• Latching alarm indicator preserves which unit first detected smoke.
• Compatible with bells, horns, repeaters and door closers from the same series.

What sensor type is inside and where should I install these detectors?

The 9120B uses an ionization sensor, which responds quickly to fast-flaming fires that produce little visible smoke early on. Place alarms on every level of the home, outside sleeping areas, and inside bedrooms for comprehensive coverage.

• Ionization sensor optimized for fast-flaming fire detection.
• Recommended placement: each floor, every bedroom, and hallways.
• 85-decibel alarm output for clear audible warnings.
• UL-tested to meet applicable safety standards.

Who is this for: Contractors, renovators, and homeowners who need reliable, easy-to-install hardwired smoke detection with battery backup will benefit from the First Alert 9120B 3-pack. It’s suited for new construction, remodeling projects, or upgrading older systems where interconnection, tamper resistance, and quick installation save time on the job while delivering dependable home safety monitoring.