This folding telescopic antenna is for your Garmin Astro/Alpha receiver. This antenna will fold down to be used with my nylon Astro/Alpha cases. Increases range over the standard rubber antenna supplied with the Astro/Alpha. In a simple test done here at the shop the distance was improved by using this antenna. The receiver dropped the collar at 1 mile using the stock rubber antenna. When the telescopic antenna was added the range improved to just over 2 miles. Antenna measures under 4" folded down, 6" unfolded, and 17.5" pulled all the way out.