This is a LaTrax #7579X metal differential gear set. Metal gears may be retrofitted into LaTrax 1/18 scale vehicles like the Teton and rally. Kit includes two output gears, four spider gears, 35T ring gear, and shaft. This product is made from high quality materials and designed for lasting performance. Use Traxxas stock and hop-up replacement parts to get the most out of you Traxxas RTR vehicles.