The removal of traditional mechanical cables in favour of electrical wires not only eliminates poor shifting caused by contaminates, corrosion and stretching, but also provides effortless gear shifts. Ultegra Di2 uses a fully removable individual cable system from the battery indicator junction box enabling fine tuning with the correct cable length to each component for easy and tidy fitment. The Shimano 6770 Ultegra Di2 Derailleur to Battery External Cable Set contains: SM-JC40 bottom bracket junction, SM-BMR1 long external type bottle cage battery mount, EW-SD50 individual wires: 1x 950mm, 1x 500mm, 2x 300mm and SM-EWC2 black stick on wire covers: 3x 300mm, 3x 50mm. Ultegra Di2 also requires a handlebar cable set to connect the shifters to a battery indicator junction box (comes with handlebar cable). External cable sets are ideal for upgrading your current bike to Ultegra Di2 if it does not feature the internal cable routing option. EW-SD50 individual wires are available in varying lengths, there is no need (or facility) to cut these cables. Reliable and secure water resistant connectors.