Shimano acera hg50 7 speed mtb cassettehyperglide sprockets have a computer designed tooth configuration with contoured shift gates resulting in a crisp smooth shift even under load close ratio gearing allows a more efficient use of energy through finer cadence control features high quality 7 speed cassette sprockets are cut away to further reduce weight without reducing rigidity nickel plated finish offers hard wearing resistance to corrosion corrosion resistant steel cassette lockring a 2