This is a Traxxas Maxx/Maxx Slash Center Differential Kit (Complete) [10280A]. The high-performance center differential absorbs driveline shocks to improve durability and distribute power evenly for mind-bending acceleration. The finned aluminum housing helps dissipate heat with a tough 44-tooth, mod 1 (1.0 metric pitch) steel spur gear for maximum durability. The sealed differential comes pre-loaded with 100k silicone oil to help prevent unloading and ballooning of the front tires.