Traxxas 5644 18T Hardened Steel Pinion Gear for 5mm Shaft, 32P (0.8 metric pitch) 18-tooth Hardened steel pinion gear Fits 5mm motor shafts 32 pitch (0.8 metric pitch) Includes set screw Use Traxxas stock and hop-up replacement parts to get the most out of your Traxxas RTR vehicles