Dyna sys 10 speed shifters with vivid indexing and 2 way release to exceed the demands of ever changing bicycle designs and riding styles light to the touch but positive and crisp vivid indexing provides a constant amount of shift lever force across all 10 sprockets 2 way release the upper lever still performs the same shift function but it can now swing in either direction allowing it to be released by the thumb or index finger multi bearing design uses two ball bearing units to provide a lo