Length of hair fibers is probably the easiest attribute to assess at a glance. Long, short, or somewhere in between - there are many different lengths from tail to tail. Most common is 2 to 5 inches, but occasionally you can find tails with 6- or 7-inch hairs, and they are coveted. Normally, a range of lengths can be found on the same tail, with the longest hairs at the base and shorter ones toward the tip. The range on a given tail will not be significant for any one length, so the tier must have an inventory of multiple tails to cover more tying situations. This may seem trivial, but I often see tiers try to tie short imitations with the tips from long fibers. The fly always loses its demeanor in the end. If you want shorter flies, you must use shorthaired bucktail or the fly will suffer.