This Hop-Up Option set is for use with XV-02 chassis cars to help protect the drivetrain from sudden surges and helps compensate for low surface grip. Slipper Plate A & B x1 each Slipper Shaft x1 Slipper Shaft Cup x1 Slipper Spring x1 Slipper Nut x1 Slipper Pads x2 Spur Gear & Spacer x1 each 1280 Ball Bearings x2 2x9.8mm Stainless Steel Shaft x1 Axle Ring x1 Compatible with XV-02 chassis cars.