First Alert Battery Powered Carbon Monoxide Alarm: * Uses an electrochemical carbon monoxide sensor * Permanent sensor lasts up to 5 years * Powered by 2 AA replaceable alkaline batteries * Test/silence button both silences the alarm and allows you to test its functionality * Monitors and re-alarms if carbon monoxide levels persist * Features a loud 85-decibel horn * No installation is required * Attractive design allows the unit to be place * Includes an optional wall mount with no outlet required * Audible and visual low battery signal alerts you to replace the battery * Pull down action chart has convenient guide on what to do if an alarm sounds * UL listed * 5-year limited warranty * Model# CO400CN2