1. Welcome to our shop! This upgraded antenna has a high-gain antenna. It is suitable for Garmin Alpha 100 50 / Astro 320 220 430 / Alpha 100 Handheld GPS. This antenna will increase the range you get. 2. It is easy to install as it has direct SMA connectors for Garmin Astro/Alpha. It connects through a standard SMA direct connection. The antenna is made of metal materials, making it durable and long-lasting. 3. This foldable and extendable antenna provides a strong and stable signal, making it very convenient to use. The folded size is approximately 25cm/9.9in, and the extended size is approximately 108cm/42.5in. The frequency range is 136-174mHz. 4. You will receive 1 x Telescopic Antenna. 5. Our customers are our top priority. If you find any product problems after receiving the goods, such as damage and incorrect quantity of goods, please contact the seller immediately. We try our best to provide you with satisfactory after-sales service.