Chamberlain Rwa300R/0120 Wireless Alert System. System Includes 1 Passive Infrared Sensor & 1 Receiver ; Extremely Easy To Use & Install--Sets Up In Minutes; Sensor Has A 30-Ft Range & Can Transmit A Signal To The Receiver Up To 1200 Ft Away ; Connects Up To 4 Sensors; Detects Humans & Vehicles, Ignores Animals ; Waterproof Sensor Assembly ; Includes Weather Shield To Protect Sensor From The Elements ; Receiver Features Sound Control & Has An Output To Trigger External Alarms Or Bells; Requires 4 Aa Batteries For Sensor Operation--Can Last For 2 Years ; Microprocessor Code-Learning Technology Eliminates False Alarms--Receiver Responds Only To Transmitters Assigned To It ; 1 Sensor Can Communicate With Multiple ;Receivers In Larger Installations ; Sensor & Receiver Each Measure Less Than 4"H X 3"W X 2"D ; 1-Year Warranty & Toll-Free Tech Support