Aluminum chassis with special cutout openings for increased flex. This chassis is recommended for and works extremely well on low-to-medium traction tracks. (Not recommended for very high traction conditions where the 301146 - Alu Chassis works better.) This alu flex chassis generates more traction and makes the car faster and easier to drive. Successfully raced by the factory team, this is a Òmust haveÓ for every serious racer.