I had the pillion and I stuck the bumper pads under the seat and not on the fender. It really seems to keep the seat from rubbing on the fender and doesn't scratch iot as bad. I got rid of the pillion because the tab that attaches it to the seat cracked, Thats the last thing I needed with the wife on the back. The bumpers are about one inch square and a quarter inch thick, made of dense foam or rubber.