Helix Race 11-speed, 511% Range, 370-Grams More Range, Less Weight The HELIX Race Cassette is an upgrade to any SRAM(TM) or Shimano(TM) 11speed shifter and derailluer combination, 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. PRODUCT FEATURES - Compatible with SRAM(R), Shimano(R), and TRP(R) Shifters and Derailleurs of the same gearing count and similar cage capacity. (Mounts on an XD driver only) - The 2-piece design allows for replaceable aluminum cogs RIDER BENEFITS - Reduces un-sprung rear wheel weight for improved suspension function and handling - Excellent shifting with Shimano(TM) and SRAM(TM) systems without compromise e*thirteen's wider range and 9-tooth cog allow riders to run a 2-tooth smaller chainring for more clearance and reduced weights - Extend the life of 11-speed components by adding gear range to an existing bike