The First Alert CO605 Carbon Monoxide Plug-In Alarm features an electrochemical CO sensor to alert you to dangerous carbon monoxide. This personal carbon monoxide detector plugs into any standard electrical socket to monitor CO levels in your home, office or other space. The simple, user-friendly design features battery backup to allow for continuous monitoring, even in the event of a power outage. Dual Power Provides Continuous Monitoring: The carbon monoxide detector can be placed almost anywhere; all it requires is a standard electrical outlet. In the event of a power failure, backup batteries power the CO detector so it can continue monitoring your space for dangerous levels of carbon monoxide. Electrochemical CO Sensor: The First Alert Carbon Monoxide Plug-In Alarm uses an electrochemical sensor to alert you to elevated carbon monoxide levels. Designed to alert the soundest of sleepers, a loud 85-decibel alarm warns you when carbon monoxide is detected. Simple and Easy to Use: The carbon monoxide monitor is easy to set up: simply plug it into a standard electrical outlet to monitor your space for carbon monoxide. There are no complicated displays or settings to navigate; a single button silences the alarm and tests the CO detector. Where To Place Carbon Monoxide Alarms: One on every level of the home and one in each sleeping area.