The HELIX R Cassette is an upgrade to any SRAM(TM) Eagle(TM) or Shimano(TM) drivetrain, with more range than other cassettes on the market. The 9 tooth cog lets you step down one chainring size while keeping the same top end gearing and provides not only better ground clearance, but an overall lighter drivetrain. - 1 aluminum cogs, 10 steel cogs - Designed for use with XD(TM) and XDR(TM) drivers only