Complete gear differential set includes a composite case and cover with integrated crown gear 35T. The internal gears are precision-molded from tough XRAY developed and mixed composite material ensuring high life time and super-smooth and efficient operation. This differential is NOT factory pre-assembled.The gear diff ensures increased on-power steering which is needed on nearly all types of tracks, and is ideal for both carpet and clay tracks. The maintenance-free diff design is a feature that will benefit racers of all levels. When the diff is correctly built, there is no need for maintenance for a very long time no need for frequent oil changes, and no leakage due to our superior sealing system.