About 800km on the cassette, with lots of life left. Shimano Dura-Ace CS-7900 Bicycle Cassette - 10 Speed Computer designed tooth configuration with contoured shift gates Allow for smooth shifting, even when under a heavy load Close ratio gearing for more efficient energy use through improved cadence control Largest sprockets are mounted onto a lightweight alloy carrier to enhance rigidity and reduce weight Nickel-plated finish offers hard wearing resistance to corrosion Includes alloy cassette lock ring. tags: cassette, sproket, duraace, dura ace, dura-ace