If you have a Motion-Activated Security Light or a Motion-Activated Lighting Control security lighting system (both sold separately) in place to receive an instant alert when visitors arrive, you can now expand your system with an Add-On Motion Sensor. The Add-On Motion Sensor sends signals to either system up to 100 feet away, even through walls and doors. The motion sensor runs on four AA batteries, sold separately.The Add-On Motion Sensor has a wide, 140-degree by 60-foot detection zone. This sensor is weather-sealed for outdoor use and long life, and an activation switch is included to specify day or nighttime operation.