This is an optional Traxxas Center Differential Kit, and is intended for use with the Traxxas E-Revo and E-Maxx trucks. The Traxxas center differential independently transfers power from the transmission to the front and rear differentials for smooth power delivery. This is the perfect solution for putting power to the ground in rough conditions and maximizing corner speed. The center differential is sealed, and can be adjusted by using different fluid viscosities for specific driving conditions. The Traxxas center differential drops directly into the E-Revo’s and E-Maxx’s gearbox, and is sold fully assembled and filled with 100K wt. silicone fluid.