First Alert CO615 Dual-Power Carbon Monoxide Plug-In Alarm w/Battery Backup uses advanced electrochemical sensors to detect dangerous carbon monoxide levels, ensuring your safety at all times. This plug-in alarm is designed with a battery backup, providing continuous monitoring even during power outages. It features an easy-to-read backlit digital screen that clearly displays detection and power status, with a calm blue light i for bedroom use. For added convenience, the alarm includes a test and silence button, along with an end-of-life warning to notify you when it's time to replace the unit. Model Number: 1039746