The Box Three E-Bike Cassette offers high gears with more teeth to withstand the rigors of modern E-Bike ridingE-Bike optimized, steel cog and spider construction for improved durabilityUltra-wide ratio with consistent progressionCompatible with HG freehub bodiesIntended for use with Box Prime 9 drivetrains only - may not be compatible with other 9 speed drivetrains12-50t9sp12-14-16-18-22-28-34-42-50BlackUPC/EAN/GTIN: 616043832852