Robinson Racing 5mm Bore, 48 Pitch Machined Pinion Gears can be used on any car that uses a 48-pitch spur, when using a motor that has a 5mm rotor shaft. Robinson Racing pinions are precision machined from high quality steel for durability and have the number of teeth stamped on the side for easy identification. Choose from multiple options to fine tune the gear ratio of your vehicle. Package includes one pinion gear and one 4mm set screw.