The 550 Motor Pinions are used for transferring power from a 550 class motor, like the HD Hex Motor or NEO 550, to a mechanism. These pinions come in three different types. The 32DP pinion gear is compatible with 32DP gears. The UltraPlanetary Pinion is used with UltraPlanetary Gearbox System and the GT2 3mm Pinion is used with GT2 timing belts. The pinions are press fit onto the 0.125” motor output shaft. Using a small drop of retaining compound, such as Loctite 609, ensures a snug fit.