Cog Sizes: 10 - 45t, 10 - 51t Cog Material: steel Freehub Type: Micro Spline Carrier Material: aluminum Includes: 1 lockring There's no need to deal with shifting that interrupts our pedal stroke when we can have the XTR CS-M9101 12-Speed Cassette, which delivers definitive shifting that lets us pedal continuously. This cassette lets us shift smoothly and quietly, and it offers increased acceleration by reducing inertia and weight. This comes thanks to Shimano's Beam Spider construction. And, using the brand's new Micro Spline freehub body and Hyperglide+ tooth profile, we're seeing some of the best MTB shifting available.