Not a clue, bought it to use on a race rep I planned to build after I sold my RS500 but gone another route now so having a clear out, I imagine it was fitted at some point by the previous owner. You have better eyesight than me if you can tell from those pics!

The rs500 moulded ones have a more rounded cut out, but being rubber I imagine it moves around the pillar anyway when offered up, easy enough to trim to shape anyway