HPI Racing drivetrain parts are standard replacement parts for Nitro RS4 3 18SS cars, and can be retrofitted to the standard Nitro RS4 3 cars for increased durability. These heavy-duty parts that are made to handle extreme conditions, racing and high output engines. They're made from high strength steel and chrome plated for extra durability and custom looks. Increased durability prevents breakage, so racers spend more time driving and less time doing repairs. The shiny chrome finish look great and gives the Nitro RS4 3 a custom look.