There are two different designs, I tried the Perspex ones but gave up on them as they always seemed to interfere with the side screens. I then swapped them for the more expensive glass and chrome type which mount on a blade sandwiched between the windscreen and the frame support, these have the advantage of folding inside the side screens when fitted. Simply a case of loosening a couple of screws, slotting the deflector in and tightening the screws. The latter type came from Simmonds.
Having gone to all that trouble I'm not entirely sure how effective any deflectors are!? Would be interested to hear other opinions.
Steve L.