The number on the line class determines the fly line’s weight, in other words, how powerful the fly rod you’re using is. That’s why the intended rod’s line class determines which line class you should choose for the rest of your gear, like the fly reel and line. A fly rod in line class 3 (#3) is a lighter rod for smaller waters and smaller fish. A fly rod in class 9 (#9) is a heavier rod designed to handle larger flies and bigger fish. When matching fly fishing gear, ensure the line, reel, and rod are of the same class. The best-selling fly fishing gear in Sweden is a 9-foot rod in class 5 with a class 5 floating line (WF) and a matching reel.
Fly line floating property
The floating property of the fly line determines how the fly will be fished. An intermediate or sinking fly line sinks, pulling the fly down to the desired depth. A floating line, as the name suggests, floats on the water surface, keeping the fly in the upper water layer.