VEXpro #25 Chain Aluminium Plate Sprockets 1 1/8in. Bearing Bore - VEXpro 217-2639, Sprockets are profiled wheels with teeth that mesh with chain to transfer motion.This VEXpro plate sprocket has a central bore hole to suit the outside diameter of a VEXpro 1 1/8in. bearing and is custom manufactured from high strength aluminium, black anodised for superior performance. The sprocket includes the VEXpro VersaKey pattern, and is compatible with all other VersaKey and VersaHub components. VEXpro 217-2639 #25 Chain 36t Aluminium Plate Sprocket 1-1/8\" Bearing Bore