The Shimano Deore XT CS-M8100 12-speed cassette is optimized with rider-tuned wide range and close step gear combinations for MTB excellence. Shift ramp designs provide fast and smooth shifts by HYPERGLIDE+ technology Light and stiff construction reduces cassette inertia resulting in faster acceleration and increased chain security Designed with a Shimano Micro Spline body that features smaller and more widely distributed splines to limit cog damage on freehub