Traxxas 2421 21-T Pinion Gear, 48P Optional Traxxas pinion gears allow you to increase or decrease the final drive ratio and tune for different applications Designed for use with 48-pitch spur gears; fits 3mm motor shafts Durable metal construction for long-lasting performance Includes set screw; one gear per package Designed for use with 48-pitch spur gears and 3mm motor shafts This is an O.E.M. part