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 Internal Cable Set contains: SM-JC41 internal junction, SM-BMR1 long internal type bottle cage battery mount and EW-SD50 individual wires: 1x 1200mm, 1x 750mm, 1x 650mm, 1x 300mm. Internal cable sets are for bikes specifically designed for Di2 to ensure clean lines and minimal rider interference. Ultegra Di2 also requires a handlebar cable set to connect the shifters to a battery indicator junction box (comes with handlebar cable). 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.