_Mega Brand Carbon Monoxide Detector, Battery Powered CO Alarm with LEDs, Test-Reset Button, Low Battery Indicator, Portable

Electrochemical sensor technology detects CO gas Easy installation, no wiring needed, detects during a power failure by operating on 2-AA batteries (included); Install on a wall of your home or place on a tabletop Green LED indicates power to the carbon monoxide detector, while an 85-decibel alarm & a red LED indicates the presence of carbon monoxide Event Memory records the last time carbon monoxide was detected or when the unit was last tested