CN: The retainer across the top performs the same function as the 'stainless strip' down each side, so you could model it after those.. If I were to guess, I'd say the portion that is 'tacked' or fastened to the roof is ~ 1/2 - 3/4" in width, and the 'foldable part' is ~ 3/8-1/2" in width. Of course the length is the width of the liftgate opening. Here's a photo I took during my w/s replacement on the '56 which shows the 'foldable' portion bent up and cleaned in preparation for installing the new W/S...