It was only a matter of time before Shimano added a cog to its XT-level cassette. The XT Dyna-Sys CS-M771 Cassette utilizes the same Hyperglide tooth and ramp shapes that were so successful in the 9-speed version, to move your chain smoothly across all 10 gears. The XT Dyna-Sys is fabricated from plated steel, which gives you a high performance cassette that doesn’t cost a premium. The spiders between the cogs are alloy and the entire 10 gears are secured with an alloy lockring.