With its Beam Spider construction, the CS-M9100 XTR 12-speed cassette shaves weight while increasing Shimano's MTB gearing range another gear. Using Shimano's new Micro Spline freehub body and Hyperglide+ tooth profile, these 10-45 and 10-51T cassettes deliver the best MTB shift experience on offer.Increased acceleration by reducing inertia and weight by Beam Spider constructionAlloy 5 beam spider carrier with 3 alloy, 5 titanium and 4 Chromoly sprockets make this a lightweight, stiff and durable 12-speed Micro Spline MTB cassetteHyperglide+ sprockets have a computer designed tooth configuration with contoured shift gates, resulting in 1/3 faster shift time than current HG cassettes providing seamless, smooth operation even under load10-45T wide ratio gearing allows a more efficient use of energy through finer cadence control in ever changing trail conditionsSprockets are cut away extensively and drilled to further reduce weight without reducing rigiditySprockets use hard anodising and