This Flexible Antenna is intended to replace the Garmin stock rubber antenna that comes with your Astro 320 and 430 receiver. This antenna increases the range that you will get with your receiver. Some test have showed up to a 25% - 35% increase in range. We stay on the conservative side when talking to our customers but there's no doubt that this antenna will add range to your system.The ranges will vary depending on conditions and terrain. This antenna has been tested and outperforms the other flexible antennas on the market. The antenna is Tuff and can withstand abuse. This antenna also outperforms the stock antenna.