The First Alert CO605 Carbon Monoxide Plug-In Alarm features an electrochemical CO sensor. It provides reliable detection to alert you to dangerous carbon monoxide levels. This personal First Alert carbon monoxide alarm plugs into any standard electrical socket. Use it to monitor CO levels in your home office or other space. The carbon monoxide alarm with battery backup offers continuous detection even during a power outage. There s no need for tools or hardware-mount installation and there are no complicated controls to learn. Its easy plug-in functionality and simple one-button operation will provide immediate peace of mind right out of the package. The loud 85-decibel First Alert CO605 Carbon Monoxide Plug In Alarm is designed to wake even the soundest of sleepers when an emergency rises.