Shimano brings 10-speed technology to their MTB groups with DynaSys shifting technology. The XT-level CS-M771 picks up where its 9-speed cousin left off with HyperGlide tooth profiles for reliable and precise shifting while a new massive 11-36 gear range will spin you up the steepest hills. Plated steel cogs ensure durability with machined cutouts to bring down the weight. The six largest cogs are pinned to two alloy separate alloy carriers three to each for further weight reduction and extra-stiff performance. Includes an alloy lockring. Specifically optimized for the asymmetric CN-HG94 10-speed chain.