This is the RC4WD Billet Aluminum Differential Case for the HPI Baja 5B SS and RTR buggies. No plastic or castings here, just strong, solid billet aluminum. Get yours while you can! These are MUCH stronger than the stock diff cases, and they are designed to handle the power and abuse being dished out by high-performance engines and off-road driving. This includes one complete diff case (two halves). The picture shows more parts to show all the details.