The Magnetic Base Long Range Rooftop Mount Antenna for the Alpha 100/200/300 and Astro 320 /220 /430extended the range of standard Garmin GPS dog tracking system. Antenna can be unscrewed from magnetic base. This powerful remote antenna magnetically mounts to your vehicle and connects to the Astro so you can track your dogs with Astro while driving. Part Number: 010-10931-00