With Di2 technology shifting is easy and precise - just a light touch, as soft as a mouse click, is sufficient for the front or rear derailleur to instantaneously select the correct gear. The removal of traditional mechanical cables in favour of electrical wires eliminates poor shifting caused by contaminates, corrosion and stretching, and also provides effortless gear shifts. TT / Triathlon single button bar end shift switches are used to operate the rear derailleur, one shifter up , one shifter down. Can be used on there own direct into SMEW90 junction, or in conjunction with STI. TT / Triathlon bar end shift switches give the added option of being able to operate the gears from two positions, either these aero extension or the STI lever while under braking which is only possible on a Di2 TT set up. Features Shifters are supplied with electrical cables installed. For use with E-tube systems. Weight: 60 grams a pair. Effortless & comfortable shifting.