Engineered for E-Bike durability and cross experience compatibility with SRAMÖ and ShimanoÖ drivetrains 9-50T combination for your 12 speed MTB allows for 2 tooth smaller front chainring, shorter chain length, more clearance and range Designed to shift with ShimanoÖ and SRAMÖ systems without compromise, so the rider can change components without concern Improved shifting performance including ShimanoÖ 12 Speed compatibility Improved interface between steel and aluminum clusters 2-piece design allows for replaceable aluminum cogs Reduces rear wheel weights, improves braking, suspension function and handling 556% range XDÖ and XDRÖ drivers only. CASSETTE HELIX+ 12 SPEED