Helix Plus 12-Speed 9-50T cassettes are a drivetrain upgrade on a budget for analog and e-bikes alike. Engineered to deliver Helix shifting precision, and cross compatibility with all SRAM™ and Shimano™ 12-speed drivetrains, the Helix Plus is also e*spec rated to withstand the rigors of e-MTB. e*thirteen's exclusive 9 tooth highest gear cog, provides a 556% gear range, and lets you step down one chainring size, while keeping the same top end gearing, meaning both better ground clearance and an overall lighter drivetrain.