This is a Team Associated Complete Gear Differential, intended for use with the Associated SC10 1/10 Scale short course race truck and includes everything necessary to build a complete differential for the SC10. This is a sealed gear differential, allowing it to be filled with silicone fluid of varying viscosities, so the diff can be tuned to suit the conditions of the track. Its also a nice option to have a spare differential in your pit box, allowing you to experiment with different viscosity fluids with less effort.