Dyna sys 10 speed shifter with vivid indexing and multi and 2 way release to exceed the demands of ever changing bicycle designs and riding styleslight to the touch but positive and crisp vivid indexing provides a constant amount of shift lever force across all 10 sprockets2 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 fingermulti release allows multiple gear changes from both levers