Dr. Pulley Variator Slides for 150cc and 125cc GY6 4-stroke engines. 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.