The Driveway Patrol Infrared Wireless Alert System keeps you aware of intruders or visitors anywhere around your home. This amazing system is wireless so you can place it anywhere that you want to monitor motion such as your mailbox, driveway, garage or any room inside your home. Just place the sensor wherever you want and keep the receiver with you and you will be alerted whenever something or someone crosses the invisible path. When an intruder is detected a pleasant yet noticeable chime is sounded alerting you of their presence long before they reach you. The weather resistant sensor installs in seconds with a screwdriver and has up to a 400 foot range. This system uses 1 "9v" battery and 3 "C" batteries (not included). The wireless receiver may also be plugged into a 4.5v DC adaptor. Features: Operates on one 9-volt and three C-cell batteries (which are not included) Sends alert when people, vehicles enter driveway or approach mailbox Wireless; motion-activated; weather-resistant; 400-foot range Sensor installs with screw on any surface: door, post, garage Portable receiver has three settings: high or low chimes Dimensions: Sensor: 4-1/4" H x 2-5/8" W x 2-1/4" D; Receiver: 5" H x 3-5/8" W x 1-1/2" D