First Alert Wireless Interconnect photoelectric smoke alarms link the alarms throughout your home. 120 V AC hardwired wireless detectors with battery backup integrate single alarms into a system. Expand protection by replacing one existing hardwired alarm with Wireless Interconnect and linking to existing hardwired and battery operated alarms. By adding Wireless Interconnect battery operated alarms elsewhere, when one alarm sounds, all alarms.. See full description for further details