The Solar Motion Sensor with Wireless Motion Alert is a convenient and affordable safety / security system. 1.weatherproof outdoor solar sensor with adjustable sensitivity control. 2. The solar sensor may be placed up to a 1/2 mile from the base unit in ideal condition. 3. Alerts with light and sound when vehicles or pedestrians approach within a 30 feet radius. 4. Expandable up to unlimited solar sensors and unlimited receiver, it is perfect for home, business, property and work site. 5. Super simple to set up. Takes only a few minutes to set up. Easy do it yourself installation. 6. Set includes one solar sensor/one receiver. Detects motion in up to 4 different zones, Low battery indicator included. 7. Receiver can be plugged in using included AC adapter or can run on (4) AAA batteries.