The HELIX R 11 Speed Cassette is an upgrade to any SRAM Eagle or Shimano drivetrain. Featuring the most range and lowest weight of any cassette on the market. compatibilityBoth the Helix R 11 and 12-Speed Cassettes work flawlessly with Shimano and SRAM 12s drivetrains, despite the challenges in designing for the different cog spacing and chain behavior. performanceThe improved performance of e*thirteen's new Helix cassette features great Shimano 12s shifting performance and improved reliability of steel and aluminum assembly. The new Intergalactic PVD finishing is twice as durable as anodized models. And it is 60G lighter. cost savingsThe aluminum one-piece 42/50 tooth cluster is easily replaceable so riders can keep their steel cluster for multiple seasons and freshen up the granny as needed without buying a whole new cassette.