The performance difference between the Rokland Outdoor 5.8 dBi Helium Antenna and the Rokland Outdoor 6 dBi Helium Antenna is minimal if at all noticeable. The two antennas are tuned in a very similar manner, and the real-world performance difference will be marginal. The more noticeable differences between our 5.8 dBi and 6 dBi antenna would be the connectors and height of the antennas. The Rokland 5.8 has a N-Male connector with a profile of 32 in. While the Rokland 6 dBi has an N-Female connector and has a low profile design using less fiberglass for lower protrusion at 21.6 in. With these differences being noted, the choice of cable and the preferred height of the antenna will be more determining factors on which antenna to choose, rather than for performance as they both produce very similar results.  You can learn more about antenna height and if that effects the gain or not in this blog post:https://store.rokland.com/blogs/news/understanding-helium-antennas