This is a set of two optional Hot Bodies light weight differential shafts, and are intended for use with the Hot Bodies D8 and D8T 1/8 scale vehicles. Lighten up your car in one of the most critical areas, rotating mass! Less rotating mass means your car will accelerate and slow down faster. Replace the original steel parts with aluminum to save weight without sacrificing strength. These aluminum differential shafts are 66% lighter than the stock shafts!