First Alert sa521cn-3st Onelink Wireless Hardwired Smoke Alarm

This First Alert SA521CN Wireless Interconnected Hardwired Photoelectric Smoke Alarm is ideal for replacing an existing hardwired smoke alarm and then installing more compatible alarms for an interconnected safety network (additional alarms sold separately). Wireless technology makes it possible for the detector to connect with up to 18 First Alert enabled alarms, so when one sounds, they all sound. The photoelectric smoke sensor is designed to reduce false alarms from cooking smoke or shower steam while remaining sensitive to real danger. The alarm uses a loud 85-decibel siren, and the smoke detector has an integrated battery backup in case of power outages and features a single button to silence false alarms and test the unit.