Scientific Anglers Fluorocarbon Leaders are not invisible underwater, let’s just say that they’re extremely hard for fish to see. Constructed of a UV-proof material with high abrasion resistance, these leaders are great for wary fish, low-water conditions, and truly excel when nymphing. But did you know they’re also great for dry-fly fishing? Just an added bonus. They feature the highest wet knot strengths in the industry and true-to-spec X sizes. You can fish the other stuff, or you can Fish the Truth.