Wireless Vibration Glass break Sensor for PiSECTOR Alarm System (WVDT-02) It will be triggered by vibration, can be sticked on the glass to sense the vibration and break high sensitivity, with a slight vibration the sensor will send alarm signals to the host , the host will alarm immediately if received the electrical wave. This is an alarm accessory, Not work along Range: 240 Feet Restricted - 450 Feet Unrestricted. Work Frequency: Compatible with all PiSector Alarm Systems battery included