Shimano's Dura-Ace Di2 Bar-End Shifters are for time trial/triathlon bicycles with Shimano's Di2 drivetrain components (sold separately). The one-button design operates only the rear derailleur, shifting up the cassette with one hand, and down with the other. This shifting setup does not operate the front derailleur and should be paired with additional satellite shifters. With a simple, light touch of the easily accessed buttons, you get instant, precise gear changes. And, these beauties feature spot-on ergonomics for smooth, controlled shifting even when you're pushing yourself to your physical limit.