It goes without saying that you need right fly fishing gear for what you are trying to achieve. This is as true for the humble fly line as it is for rods, reels, lures and flies. The size and type of fly lines all comes into play. Different companies such as Scientific Anglers, Cortland, AirFlo, and others use the same definitions for their lines. For example, 6-weight fly line is designated for a 6-weight fly rod. Variations from company to company are more about core of the line, the hardness or softness of the outside material or, in the case of a floating line, how high the floating line rides.
Before you begin fishing you need to decide on whether you’re going wet or dry, with short or long cats, delicate presentations or slogging nymphs or streamers. "DT", originally a budget line which meant if it was worn or cracked you could take it off the reel and wind the worn end against the backing. It is also tapered on both ends. It was originally marketed as a budget line. The DT has been used for many years as a dry fly line. A recent innovation, the "TT" for Triangle Taper has a longer distance of taper. It casts well, rolls out smoothly, making it not just a great dry fly line, but also excellent for roll-casting.
More on this subject next time. But do check out our shop for the lines we have on offer. We can supply all of your fly fishing gear, no matter what the conditions or your experience level.