The External Antenna increases GPS reliability and accuracy and is strongly recommended for vehicles with a heat-reflective coating on the windshield. Comes with a magnetic base for easy mounting and a 3.6 meter cord (12 feet). The antenna cannot be connected directly to the following GPS units, Magellan RoadMate 2200T, CrossoverGPS, and Maestro 4040. You must use the enhanced TrafficKit cradle made for them. (Sold Separately)