DESC: 9V, Battery Carbon Monoxide Alarm, No Installation, Provides Safety Needed During A Power Outage, Single Test & Silence Button, Permanent Sensor Never Needs Replacing, Battery Included, Front Access Battery Door Makes Changing Battery Easier, Unique End Of Life Alarm, 3 Chirps To Indicate End Of Life, 85 Decibel Loud Alarm, 5 Year Limited Warranty, 5 Year End Of Life.