This is the shimano dura ace 9000 11 speed road cassette rider tuned means dura ace works the way you want it the new 11 speed road cassettes are available in a range of sizes including a wide range 11 28 option one cassette to use all year round smooth fast shifting guaranteed featuring a carbon mid spider carrier and titanium sprockets 16t and bigger lighter than cs 7900 10 speed sprocket 11 25t