The optional center differential transfers power to the front and rear differentials independently for smooth power delivery in rough conditions and maximum corner speed. The sealed differential can be adjusted by using different fluid viscosities for specific driving conditions. The center differential comes fully assembled and ready to install with 50-T, 52-T, and 54-T spur gears. (Center differential kit requires 32-pitch pinion gear.) For off-road use with NiMH and 2-cell LiPo batteries only. For 3-cell LiPo compatibility, Traxxas recommends the 6780 center differential kit.