The Kidde 5CO Battery Operated Carbon Monoxide Alarm - White continuously monitors your home for the presence of deadly carbon monoxide gas. It features two distinct LED lights: a red LED that illuminates upon detection and a green LED that confirms the alarm is operational. This portable unit is supplied with 3 x AA alkaline batteries and offers a 7-year sensor life with an end-of-life warning, ensuring constant protection and a loud 85dB alert when needed.