This is the Novak 5mm 32-Pitch Steel Pinion Gear 3-Pack. These pinion gears are ideal for Traxxas Slash 4x4 trucks using the Novak HV 550 motors, as well as any vehicle that uses 32 pitch gears and a motor with a 5mm shaft. Novak hardened steel pinion gears are now available in three packs! This allows drivers to experiment with gear ratio changes, while at the same time saving money by giving drivers the option to purchase a pack of gears, instead of buying individually!