This is the Optional Steel Spur Gear for the Nitro T-Maxx and Nitro Rustler This mounts to the spur gear shaft and is driven off the clutch bell FEATURES: Strong steel construction Silver in color Bearing pre-installed YOU WILL RECEIVE: One 72t steel spur w/bearing pre-installed REQUIREMENTS: Assembly onto kit SPECIFICATIONS: Thickness: 4mm Diameter: 60mm COMMENTS: This is a direct fit and replaces part#4472 jim 01/18/01 &