Chamberlain Wireless Motion Alert System Sensor Add-On: * Extra sensor to be used with the Wireless Motion Alert (model CWA2000) - up to 4 sensors can be used with each base station receiver * Box contains 1 motion sensor, mounting bracket, and hardware. * Transmits signal to base station up to a half-mile away * Detects motion up to 30 feet away with wide 120 degree coverage * Adjustable sensitivity controls help prevent false alerts * Wireless, weatherproof design makes it portable for use inside or out * Easy to install, use, and maintain * Requires four AA batteries * 1-year warranty