The 5815 is the ideal solution for installations where small size and aesthetics are important. It provides a reliable, convenient, and cost-effective solution for door and window protection. With a demonstrated outdoor range of over a mile, the 5800 Series has the best performance of any transmitters available today. Features: -New sleek design -Two reed switches -Transmits supervisory, tamper and low battery messages -Battery: 3V Lithium -Dimensions: 3in H x 1-1/2in W x 7/8in D