The Extreme Heavy-Duty Upgrade Kit transforms your already-tough Hoss^® 4X4, Rustler^® 4X4, or Slash^® 4X4 into the ultimate bashing machine. Engineered for extreme brushless power systems, the kit includes a full complement of driveline and suspension parts designed to work together as a complete package. Whether you're sending it at the skate park or preparing for a speed run, the Extreme Heavy-Duty Upgrade Kit is battle-hardened to withstand brutal punishment and come back for more.