This Kyosho factory replacement gear set is designed for the Optima platform and includes the differential ring gear assembly along with two additional spur gears of differing sizes. The set provides the core metal gearing components needed to service or rebuild the Optima drivetrain. The differential carrier features an open-cage design with internal drive slots for the diff internals. Features: Metal construction throughout Includes differential ring gear carrier and two spur gears Fits Kyosho Optima platform 7/7/26 cs