Optional parts for INFERNO MP10 series and MP9 series. Light weight 47T spur gear for use with smaller diff for the center(Same as front and rear diff). By using the smaller diff, acceleration will be quicker and smoother. Smoother deceleration can also be achieved. This spur gear is design to fit the smaller diff case replacing the stock diff housing which is larger. Requires to use with IF403B Diff case set.