NEW Kidde Electrochemical Sensor: Most accurate CO sensor technology available - No replacement required. 85db Alarm: Alerts you if carbon monoxide levels become dangerous. Battery Operated: Provides protection during power outage. Test/Reset Button: Tests unit's electronics and silences sounder alarm. Snap Open Cover: Gives you immediate access to batteries. 5 Year Limited Warranty UL Listed Part #: 9CO-5 Model #: KN-COB-B Size: 7.25" W x 1.75" D x 11" H Weight: 1 lb