This Associated factory replacement pinion gear is a 15-tooth, Mod 1 design sized for a 5mm motor shaft, built from steel for durability in demanding 1:8 scale competition use. The set includes the pinion gear and a set screw for securing it to the motor shaft. It is a direct-fit replacement for Associated 1:8 electric platforms. Features: 15-tooth Mod 1 pinion gear 5mm shaft bore Steel construction Includes set screw 7/7/26 cs