Wireless driveway alarm, electromagnetic technology detects vehicles entering & exiting driveway & alerts you with indoor chime, up to 400' range from indoor receiver to driveway sensor, does not detect people or animals, transmitter requires 2 "aa" batteries, not included, note: use lithium alkaline aa batteries in colder climates, sensitivity adjustment 3' to 12' radius, dip switches for personalized transmission codes, 1 year warranty.