This is an #8052 39-tooth spur gear for the 1/10 Traxxas trx-4 scale and trail crawler. Use Traxxas stock and hop-up replacement parts to get the most out of your Traxxas RTR vehicles. This product is made from high quality materials and designed for long-lasting performance. This is replacement hardware for use on Traxxas vehicles; consult your user's manual for exact parts listings.