The Garmin Alpha Magnetic Mount Antenna attaches to your vehicle to substantially extend the reach of Garmin handheld tracking units; perfect for hunting with hounds out of a truck or searching for a lost pointer that ranged too far. You simply replace the SMA connection on the handheld from the original antenna to the magnetic mount antenna, unwind the amount of cable that you need (11 ft. max), then attach the magnetic mount to the hood of your truck at least 3 ft. away from other transmitting antennas. This 17 in. long antenna increases the range and strength of the signal by miles, depending on the terrain, and continues to track the TT10 dog collar even when the vehicle is in motion. Compatible with the Garmin Alpha, Garmin Astro 220 or Garmin Astro 320 tracking handhelds. This is not a cheap after-market product, this is high-quality Garmin gear.