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. 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 SPECIFICATIONS TECHNOLOGY HIGHLIGHTS: X-DOME(TM), XD(TM) driver body, X-GLIDE(TM) 2 SPEEDS: 12 COLORS: Black RECOMMENDED CHAIN: Eagle(TM) chain Only RECOMMENDED GROUP: X01 Eagle(TM) COMPATIBILITY: 12-speed XD(TM) driver body compatible