FM231 Vehicle Exit Sensor, Wireless Gate Exit Control, Operation 400 ft Range Between Transmitter & Receiver, Adjustable Sensitivity From 3-12 ft Radius. Rejects Line Noise at 50 Hz & 60 Hz, Long Battery Life (1-3 yr) Due to Low Power Consumption. Sensor Detects Vehicle-in-Motion, Similar Operation to a Loop System without Having to Cut Asphalt, Color Black, Length 16 3/4 in, For Use With 8DFT2, 8RLJ4, 9JH02, 9V219, Includes (3) Mounting Posts, Receiver, Sensor, Transformer, Transmitter Module