Take a quick look at the new X-DOME(TM) Eagle(TM) cassette. The last dangling shred of an argument in favor of a mountain bike front derailleur is now officially dead. Designed for use with our proven, reliable XD(TM) driver body. It carries with it the X-DOME(TM) architecture, which, independent tests have concluded, yields the strongest cassettes on the market. New shifting characteristics improve both, inboard and outboard shifting, as well as chain retention. SRAM&&';;s cassette manufacturing technology provides the greatest durability and lightest weight All-new shifting features create a smoother, quieter system with enhanced inboard and outboard shift performance XD(TM) driver body compatible 10-52: 10, 12, 14, 16, 18, 21, 24, 28, 32, 36, 42, 50, 52 10-50: 10-12-14-16-18-21-24-28-32-36-42-50 SPECIFICATIONS TECHNOLOGY HIGHLIGHTS: X-DOME(TM), XD(TM) driver body, X-GLIDE(TM) 2 MATERIAL: Same as XX1, machined chromoly 11t cog cluster with aluminum 50t cog SPEEDS: 12 COLORS: Gold RECOMMENDED CHAIN: Eagle(TM) chain RECOMMENDED GROUP: XX1 Eagle(TM) COMPATIBILITY: 12-speed XD(TM) driver body compatible