Shimano Dura-Ace R9160 Di2 TT Bar End Shifters 1-Button Design Syncro Shift compatibleShimano Dura Ace R9160 Di2 TT Bar End Shifters 1 Button Design Syncro Shift compatible. Shimanos Dura Ace SW R9160 TT bar end shifters feature a refined ergonomic shape and simple single button design. Provides quick shifting while riding in the aerobars Utilizes Shimano synchronized shift program allowing each bar end shifter to be programmed to upshift or downshift the rear derailleur while the Di2 computer decides when to shift the front derailleur