Upgrade your bike to the smooth, precise shifting of an electric drivetrain with Shimano's Dura-Ace Di2 Electronic Shifting Components Kit. Say goodbye to cables stretching, constant derailleur adjustment, and say hello to instant, precision shifting time and time again. With a simple, light touch of the easily accessed shift buttons on the svelte Dual-Control levers, you get amazingly smooth, quiet gear changes front and rear. And forget about trimming the front derailleur because the Di2 does it automatically so you never have to deal with rubbing again. The shifting is powered by a rechargeable, sealed Li-ion battery with enough run-time on each charge for about 1,500 miles. And, the levers boast a new ergonomic shape and hoods to match for a superb feel when you're churning out the miles. If you're ready for the cutting edge in drivetrain technology step up to Di2 and experience the future today.