This is the Optional 32P 72T Spur Gear for the Traxxas T-Maxx Truck. This mounts to the spur gear shaft and is driven by the clutch bell. FEATURES: Strong nylon construction Black in color YOU WILL RECEIVE: One 72T spur gear (main gear) REQUIREMENTS: Assembly onto the kit. SPECIFICATIONS: Tooth: 72 Pitch: 32 Thickness: 5.6mm COMMENTS: This is a direct fit hop-up. Reference the T-Maxx manual for different ratio combinations. Using a smaller tooth spur gear will give you higher speeds, and using a larger tooth spur gear will give you more torque. jim 1/18/2001 ir/jl