Shimano XT CS-M8100 Cassette - 12-Speed, 10-45t, Silver/Black, Micro SplineThe Shimano Deore XT CS M8100 12 speed cassette is optimized with rider tuned wide range and close step gear combinations for MTB excellence. Product Details: Designed with a Shimano Micro Spline body that features smaller and more widely distributed splines to limit cog damage on freehub Light and stiff construction reduces cassette inertia resulting in faster acceleration and increased chain security Shift ramp designs provide fast and smooth shifts