The First Alert SA521CN-3ST Interconnected Smoke Alarm with Hardwire Adapter Included allows you to create an interconnected fire alarm system without the hassle of wiring. Use this smoke detector to replace an existing hardwired smoke alarm and then install additional First Alert wireless alarms for an interconnected safety network (additional detectors sold separately). This hardwired smoke and fire detector can connect and communicate with up to 18 compatible alarms, so when one alarm is triggered, the entire system will sound. Equipped with battery backup, this smoke and fire alarm allows for protection during power outages.
Create an Interconnected Fire Safety System: The First Alert Interconnected Smoke Alarm with Hardwire Adapter Included makes it easy to begin creating a safety network of detection. This detector is designed to replace an existing hardwired 120-volt alarm so you can add up to 18 First Alert wireless interconnected alarms By connecting multiple wireless interconnected detectors, you can be alerted to danger on the other side of your house before the smoke from that area reaches you. When one alarm sounds, all connected alarms in the system will sound simultaneously.
Hardwired Smoke Alarm: The smoke detector is designed to easily replace most existing 120-volt hardwired alarms. Equipped with an easy adapter plug, there is no need to rewire when installing the fire alarm. Also, in case of power outages, the smoke detector has a battery backup feature designed to ensure continuous protection. A low-battery light and chirp will let you know when the AA batteries need to be replaced in the smoke detector.