The ELK-319WS is a Supervised, Wireless Window Sensor designed to detect the opening of a window or vibrations made by an intruder attempting to break the window. A built-in reed switch monitors window movement and a piezo shock sensor monitors vibrations. This sensor is compatible with Elk's 319MHz Receivers/Panels as well as many other panels that operate on the 319.5MHz frequency. ELK's 319 Series Sensors are ideal for Interlogix systems in need of replacement sensors.