The Dura-Ace Di2 front derailleur features an electric motor worm drive and fabulously fast shifting. Noisy and sloppy front shifting are virtually eliminated. The intelligence of the Di2 system knows exactly the gear that is being utilized and centers the front derailleur perfect around the chain. It also makes perfect shifts every time without dropping the chain on the inside or throwing it off the outside. The Dura-Ace Di2 front derailleur is one part of the Di2 system including shifters, derailleurs, battery, battery charger, and several cables/wires.