This Associated factory replacement pinion gear is designed for a 2.3 mm motor shaft and features 0.5 module tooth pitch with a 14-tooth count. It is built for the Associated MT12 platform and is the correct spec gear for maintaining proper drivetrain mesh in that application. The pinion includes a metal set screw for securing it to the motor shaft. Features: 14-tooth count 0.5 module pitch 2.3 mm shaft diameter Includes set screw 7/7/26 cs