Rear Mud deflector
It is made of stainless steel and fits onto the number plate. It hangs straight down from the plate and then angled outwards away from the rear of the bike.
Stops all the crud from flying up and then being sucked into the pillion passenger caused by the vortex swirl effect. The only portion that shows from the rear is about four inches in length by the width of a standard number plate
Hope that helps.
It is also very neat.
Regards
Dan