When every second counts, you want Shimano's Dura-Ace Di2 Dual Control Electronic Bar-End Shift/Brake Levers at your disposal. These amazing time trial/triathlon-specific levers are for use with Shimano's Di2 drivetrain components (sold separately). With a simple, light touch of the easily accessed buttons, you get instant gear changes, and the brake levers offer smooth, well-modulated control right at your fingertips.