Hardwired 120v Electrochemical Carbon Monoxide Alarm

First Alert hardwired carbon monoxide detector with battery back-up. Features an electrochemical sensor which detects carbon monoxide gas and measures the concentration. Sounds a loud 85 decibel alarm when potentially harmful level is reached. 2 silent features; unwanted alarms and low battery silence. Instant test/reset button. 9-volt battery included. Battery life varies according to use and application. Recommended for professional installation only. UL (Underwriter's Laboratories) listed. White.