Shimano have retained the traditional close cassette ratios from previous editions of Dura-Ace, but with the new R9100 groupset they have also introduced a wide range 11-30T cassette. All cassettes in the range will be compatible with the one rear derailleur so you can easily swap your cassettes out based on terrain.
The cassette is manufactured from a lightweight alloy and carbon fibre spider that houses 6 alloy sprockets and 5 titanium sprockets. The largest sprockets are manufactured from titanium to keep the weight low. The sprockets are also extensively cut away and drilled to further reduce weight without reducing rigidity.
The very best and quickest shifts are optimised thanks to the Hyperglide EV sprockets that have a computer designed tooth configuration with contoured shift gates.