The XX SL Eagle Transmission (T-Type) Cassette is a major reason why Eagle Transmission offers the best-ever inboard and outboard shifting performance under load. Thanks to its full X-SYNC design, the harder you pedal, the better it shifts. This is the lightest Eagle cassette in history as well as our most precise and long lasting. Its new-gen features a fully machined, hardened steel X-Dome architecture for gears 1-9 and an ultra-lightweight, all-aluminum Spider Cog for gears 10-12. Engineered as integrated and interdependent transmission components, the XX Eagle Transmission Cassette and derailleur contact directly, ensuring perfect alignment on every bike. From its massive 520% gear range, the 52 tooth cog steps down with improved gear progression with 44 and 38 tooth cogs in the low end (compared to the Eagle drivetrain 10-52-tooth cassette). Featuring a clearly marked Setup Cog, install is both simple and fool-proof.