Shimano sora hg50 9 speed road cassettehigh quality 9 speed cassette hyperglide sprockets have a computer designed tooth configuration with contoured shift gates resulting in a crisp smooth shift even under loadfeatures close ratio gearing allows a more efficient use of energy through finer cadence control sprockets are cut away and drilled to reduce weight without reducing rigidity nickel plated finish offers hard wearing resistance to corrosion corrosion resistant steel cassette lockring fo