First Alert CO600 Plug-In Electrochemical Carbon Monoxide Alarm. Utilizes an electrochemical carbon monoxide sensor. This carbon monoxide detector plugs into any standard electrical outlet and features an end-of-life warning alerting you when to replace the detector. When carbon monoxide levels become elevated, a loud 85-decibel alarm alerts you to the threat. Uses an advanced electrochemical CO sensor to detect elevated carbon monoxide levels. When CO is detected, the carbon monoxide detector sounds an alarm to warn you of the threat. Features an 85-decibel siren that is designed to wake even the soundest of sleepers. A low-battery light and alarm alert you when battery power is running low, and an end-of-life timer lets you know when the device should be replaced. Lasts approximately five years. No complicated displays or settings to navigate - a single button silences the alarm and tests the CO detector. A pull-down action chart instructs you in what to do if the CO alarm goes off.