BOX Two Prime 9 Groupset Single ShiftIncludes cassette, derailleur, shifter and chain Single shift options are for eMTB to keep the user from shifting multiple gears under load, significantly reducing the rate of bent teeth and broken chains Cassette fits HG splined Shimano SRAM 8 10sp freehubs 3rd party web sales must be an Authorized Dealer TECH SPECS model Box Two Prime 9 freehub type HG speed 9 range 11 50 shifter single shift color black