This is the emergency light that also monitors a home’s carbon monoxide levels and notifies you when CO is too high. The device plugs into an outlet to provide nightly illumination in a hallway while constantly monitoring the air for CO. When CO levels are too high, the device flashes its light and sounds an alarm. During a power failure, the built-in rechargeable battery maintains illumination for one hour and CO detection for up to seven days. The device has three bright LEDs and its outlet prongs fold into the unit, allowing it to be used as a flashlight. 5 1/4" H x 2 2/3" W x 1" D. (4 3/4 oz.)