Di2 electronic shifting enables a whole new level of riding that can't be experienced through traditional mechanical shifting, by offering smoother, faster, more precise and nearly flawless shifting. Now time trialists and triathletes can sink their teeth into Di2 technology. The SW-R671 Remote TT Shifters mount to aero extension bars, allowing instant shifts while in the aero position. With multiple control positions, quick and accurate shifts are always close at hand, while the two button design controls both the front and rear derailleur. The SW-R671 TT Shifters are customizable just like all the other Di2 shifters, and allows you to create customized shift maps and fine tune performance to even the most specific of needs. Take your time-trial / triathlon bike to the next level with a Shimano Di2 Ultegra system.