The original (glass) rear screen has the tendency to break when it encounters a stone. This will result in an enormous amount of glass pieces all around the interior and scratches on the rear clamshell.
As a bonus, it will safe you weigth!
This version of the rear screen is to be glued into the original rubber of the later models of the Elise S1. It will not fit a standard Elise or a later Elise without the original rubber frame. (direct replacement for the glass screen)