I apologize that the website is not really clear. We will be making some changes to it to clear it up a bit.
There are two different style CDW's-
1. Fits HD Trikes with a tank lift and looks like this-
2. Fits Trikes without a tank lift and all 2 wheel Touring models (with or without a tank lift) and looks like this-
The reason for the different design is that on all two wheelers, and Trikes without a tank lift, there is less clearance room, so the design is a bit different (and smaller) to get everything to fit.
They both have a "wing" to them that extends out past where the air is that would cause buffeting, this wing is to catch extra air and direct it down onto the engine.
The purpose for designing these was two-fold:
1. Redirect air onto the engine to cool it down. This happens 100% of the time and is good for an 8-15* reduction in engine temps (regardless of design).
2. Reduce buffeting. How much it will reduce it is dependent on dozens of factors. How tall you are, what kind of seat you use, how you sit/slouch, foot/leg placement, type of helmet, etc.
Here are a few photos, side by side, for comparision-
btw, the one made for the two wheelers/trikes with no tank lift, will also fit on the trikes with a tank lift.
Kevin