Wireless Interconnected Hardwired Photoelectric Smoke Alarm, Wireless Technology Makes It Possible For The Detector To Connect With Up To 18 Compatible First Alert Wireless Enabled Alarms To Create A Wireless Safety Network, Additional Alarms, Not Included, Connected Alarms Can Communicate With Each Other Sound In Unison, The Photoelectric Smoke Sensor Is Designed To Reduce False Alarms From Cooking Smoke Or Shower Steam While Remaining Sensitive To Real Danger, Smoke Detector Has An Integrated Battery Back Up In Case Of Power Outages Features A Single Button To Silence False Alarms Test The Unit, Hard Wired, Ionization Sensor Type