Kidde Carbon Monoxide Alarm 900-0263: Electrochemical sensing technology - plug-in carbon monoxide alarm detects invisible carbon monoxide gas Protects during a power failure: 2-AA batteries (included) provide backup in the event of a power outage 85 decibel alarm alerts of carbon monoxide Easy to install & use: AC powered by your standard wall outlet Place 1 carbon monoxide detector on each level of your home & in each bedroom to help protect from poisonous CO gas End of life notification warns of replacement need after 10 years Test & reset button ensures of proper operation Two LED's: red for alarm mode and green for normal operation UL Certified, 10-year limited warranty