e*thirteen Helix R Cassette - 12-Speed, 9-50t, Eggplant

Works flawlessly with Shimano and SRAM drivetrains, including electronic shift systems
CNC optimized for light weight and wide range
Helix R is durable and serviceable, with replaceable gear clusters
Engineered with improved durability of 2 part steel and aluminum assembly
XD driver compatible
1.28 pounds