Shimano SL-M4100-R

This rear shifter features a 2-way release, which allows shifting from various riding positions. This means that its upper lever still performs the same shift function, but it can now also swing in either direction, allowing it to be released by your thumb or your index finger.Technologies:2-way Release: 2-way release allows shifting from various r... moreiding positions; 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.Vivid Indexing: Light to the touch but positive and crisp, Vivid indexing provides a constant amount of shift lever force across all 10 sprockets.Dyna-Sys 10-speed Compatible: For use with precision 10 speed MTB drivetrains.