The Medallion Series Wireless Carbon Monoxide Detector with Transmitter signals you when there are dangerous levels of odorless and invisible carbon monoxide gas build-up. Transmitter signals any Medallion Series Receiver. Easy installation in any room, powered by a long-life 3-volt lithium battery (included) for round-the-clock 24-hour protection. Range up to 200 feet (61 meters) depending on conditions or receiver used. Features the Silent Call Combination 3- and 5-year limited warranty. Manufactured in the USA.