E*thirteen Helix Race 12sp Cassette 13-52t - IntergalacticWork flawlessly with Shimano, SRAM, and TRP 12sp shifters, regardless of different cog spacing and chain behavior Improved reliability of a steel and aluminum assembly The Intergalactic PVD finishing is twice as durable as anodized models Designed for steep terrain where climbing time and shift frequency is high and descents are gravity driven, allowing optimized cadence and torque for more efficiency during climbs with smoother shifts under load for