The rollers on the piston are indeed the same size and shape as the door drive and clutch retractor rollers. However, they are made of a different material that is much more oil resilient. They are supposed to be blue in color. The door drive rollers are red and very firm. The clutch retractor roller is black and very soft. The black rollers will quickly disenegrate. The red will last longer, but run rougher. The blue will give optimum life and smoothness in ride.