First Alert BRK 7010B Hardwire Smoke Alarm with Photoelectric Sensor and Battery Backup 120-volt hardwired smoke alarm wires directly into your home's electrical system Photoelectric sensor detects smoke from smoldering fires while minimizing false alarms Universal mounting bracket and plug-in power connector for hassle-free installation Equipped with Optipath 360 for more comprehensive detection Smoke detector can integrate with up to 18 compatible devices for extended coverage