I am bidding a project that has Pella Windows in varying sizes. In the Shade Tool Program it is defaulting the Roller 64's. One long shade 14 feet in width I need a Roller 100 Motor but was wondering why and when would I want to try Roller 20 motors? Is it based upon only window square footage? Or is it based upon bracket size fitting in the pocket. Any links to bracket size will help in making the install look clean.