ducksterman,

Are you looking to get a Sinking Fly Line or a Sinking Tip Fly Line? In either case, checkout Scientific Anglers website. They have both a Fly Line Selector and PDF downloads of the various types that will help you decide. One of the most important feature to consider when selecting a sinking line is its sink rate. This allows you to get to a desired depth.

This year I used SA Uniform Sink + and have been very pleased with it. I believe it is the Type II sink rate.