The carbon monoxide detector alarm continuous monitoring of Carbon Monoxide levels to keep your family safe. Operated by 2 * 1.5V AAA batteries (not included),portable and easy installation,no need for socket, not affected by power failure, can be installedanywhere Features an advanced electrochemical carbon monoxide sensor that accurately detects carbon monoxide levels, no matter where the detector is placed in the room.To ensure complete protection make sure to place one on each level of your home and in eachbedroom. Simple to use,with a single test/reset button,when a dangerous level of carbon monoxide is detected the red LED will flashes and a loud alarm pattern will sound--Loud 85 decibel alarm with LED Flash.