When a person opens a door or window that you’re monitoring, you'll receive an instant notification with the Medallion™ Series Door/Window Access Transmitter. It connects by wire to two magnetic contact bars mounted on the door or window and its frame. When the door or window is opened and the bars lose magnetic contact, the transmitter broadcasts a signal to any Medallion™ Series Receiver, alerting you to the event. Easily installed, it operates on two AA batteries.