First Alert FCD4CN-3 Battery Powered Carbon Monoxide Alarm Plug-in with battery backup. Works during power outages Remote control Silence/Test. Uses most remote control devices to silence or test alarm. Digital Display. Stores, recalls, and displays highest level of carbon monoxide detected. Simple to use silence/test button; low battery warning; end-of-life timer and loud 85-decibel alarm 5 year limited warranty