Traxxas 3951 21-T Pinion Gear, 32P Optional Traxxas pinion gears allow you to increase or decrease the final drive ratio and tune for different applications Precision machined-steel construction Designed for use with 32-pitch spur gears; fits 3mm motor shafts Machined to remove unnecessary weight Includes set screw; one gear per package Use Traxxas stock and hop-up replacement parts to get the most out of you Traxxas RTR vehicles This product is made from high quality materials and designed for lasting performance This is for use on RC vehicles, consult your user's manual for exact parts listings