Traxxas gear, 13-t pinion (0. 8 metric pitch, compatible with 32-pitch) (fits 5mm shaft)/ set screw 38-5642 description: 13-tooth pinion gear (32-pitch) fits 5 mm motor shafts and includes set screw. Traxxas pinion gears let you fine-tune the performance of your traxxas model. Changing gear ratios can help balance acceleration and top speed for different running conditions. Please consult your owners manual for more information on recommended gearing options for your specific model. Accessory part for these models: hoss 4x4 vxl