Take a quick look at the new X-DOME Eagle 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 driver body compatible Technology: X-DOME, XD driver compatible, X-Glide 2 Machined cromoly 11t cog cluster with aluminum largest cog Speeds: 12 Recommended chain: Eagle chain Gear Ratios: choose; 10-50t, or 10-52t Cogs: 10-12-14-16-18-21-24-28-32-36-42-50 (10-50t); 10-12-14-16-18-21-24-28-32-36-42-52 (10-52t)