This is the Castle Creations 48P Pinion Gear with 5mm Bore. Designed to offer a high strength 5mm bore option for 1/10 scale vehicles, this 48P pinion has been constructed from carbon steel. This incredibly strong material matched with the precision of being CNC machined and a high wear case-hardened finish gives you a top tier pinion option. Package includes one pinion gear with set screw.