Dr. Pulley Variator Slides SP2517-P Dr. Pulley Variator Slides for the Piaggio X9 500, Piaggio MP3 400 and Piaggio MP3 500. The Slide Pieces in the variator are equally as important as the rollers. It is highly recommended to change the slide pieces to coincide with the rollers. The Dr. Pulley Variator Slides are made of the same abrasion-resistant nylon as the Dr. Pulley Roller Weights, which promises a long life. Set of 4