Style:Plug in Alarm with Digital Display | Size:2 packProduct DescriptionThe First Alert CO615B dual power carbon monoxide plug in alarm alerts you to dangerous carbon monoxide. This carbon monoxide detector operates on a dual power system with battery backup for continuous monitoring, even in the event of a power outage. The backlit digital screen tells you at a glance what the carbon monoxide and power Levels Are. The Co monitor also features a convenient test and silence button and an end of life timer that lets you know when it is time to replace the unit.*ensure the outlet has power.*the battery is for back up only and is not intended to power the alarm for an Extended period of time in the absence of AC. *the alarm will light up the display briefly to indicate the unit is receiving power. *press and hold test button to ensure activation.Carbon monoxide (CO) is the leading cause of accidental poisoning deaths in America, yet many people don't know they are suffering from CO poisoning until its too late. Since symptoms of CO poisoning are like the flu, you might not even know you're in danger at first. That's why a carbon monoxide alarm is an excellent way to protect your family. It can detect the CO you can't see, smell or taste in the air.The First Alert CO615B carbon monoxide alarm uses an electrochemical carbon monoxide sensor-the most accurate technology available. Installation is as simple as plugging it in to any wall outlet. Its easy-to-read backlit digital LED display gives you a clear read-out of current CO concentrations in parts per million. The alarm includes a battery back-up giving you peace of mind in a power outage. The test/silence button both silences a non-threatening alarm or low battery warning and allows you to test the unit's functionality. The unit monitors and re-alarms if carbon monoxide levels persist sounding a loud 85-decibel horn. An audible and visual low battery signal alerts you to replace the battery and an indicator alerts you when a battery has been removed. An end-of-life alarm of three chirps alerts you to replace the unit. Two AA batteries are included. 7-year limited warranty. UL listed.What's in the BoxOne carbon monoxide alarm, two AA batteries, and user's manual