The Fortress Total Security Motion Detector uses passive infrared technology to detect motion and provide added security at your home or business. It is used to sense movement of people, animals, or other objects. These sensors will detect motion up to 30 feet from the device. With a viewing angle of 110 degrees horizontally and 90 degrees vertically, the dynamic range gives you an extra piece of mind. Communication back to the main panel is approximately 250 feet depending on obstructions. Convenient built in switches can control the time between triggering events and the LED indication light, which can save you battery life. The Total Security Infrared motion detectors operate with two AAA batteries and must be paired with the Total Security System.