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.