Shimano CS-771 Deore XT 10-speed CassetteHigh performance 10 speed Dyna Sys cassette Hyperglide sprockets have a computer designed tooth configuration with contoured shift gates, resulting in a crisp smooth shift even under load Close ratio gearing allows a more efficient use of energy through finer cadence control Six largest sprockets are mounted on lightweight alloy carriers to reduce weight and increase rigidity Sprockets are cut away and drilled to further reduce weight without reducing