The First Alert CO605 Plug-In Carbon Monoxide Detector helps protect your family with an electrochemical sensor and an 85-decibel alarm, and easily plugs into any standard outlet with no additional mounting necessary. It also includes a battery backup, so CO is monitored even if there's a power failure. One button silences any nuisance alarms, and also tests detector functions. And an end-of-life signal enhances your safety by letting you know when it's time to replace the unit. Keep your family safer by installing units on multiple levels and in each bedroom.