Shimano EW-SD50 E-tube Di2 electric wire, 300mm. The removal of traditional mechanical cables in favour of electrical wires not only eliminates poor shifting caused by contaminates, corrosion and stretching, but provides effortless gear shifts. E-tube 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. EW-SD50 wires are required to connect the junction (either SM-JC40 external or SM-JC41 internal to the rear mech, front mech, battery and to the handlebar battery indicator junction box. EW-SD50 are not designed to be cut, therefore are available in a a range of lengths. Suitable for use with Dura-Ace and Ultegra. Reliable and secure water resistant connectors. Official Shimano part.