Four Carbon Fibre carriers & 6 titanium sprockets make this Shimanos lightest 11-speed Dyna-Sys MTB cassette Hyperglide sprockets have a computer designed tooth configuration with contoured shift gates resulting in a crisp smooth shift even under load 11-40T wide ratio gearing allows a more efficient use of energy through finer cadence control Four separate lightweight carbon fibre carriers reduce weight & increase stiffness giving more precise faster shifts 35/31/27/24/21/19T sprockets are all made from Titanium to reduce weight & increase durability Sprockets are cut away extensively & drilled to further reduce weight without reducing rigidity Nickel-plated finish offers hard wearing resistance to corrosion Alloy cassette lockring For use with 11-speed SIL-TEC chains