Shimano Ultegra EW-SD50 is a dual core electric wires with Di2 technology. Dual core wires inside thin electric cables with 5.1mm diameter connectors at each end. They come in different lengths to streamline all connection points and keep everything on your bike looking neat and tidy. Digital operation has many advantages including lightning fast response to signalled actions, effortless gear shifts and longer product durability due to the absence of depreciating factors such as contaminates, corrosion, and stretching.
The Ultegra 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. Setting up the wires with the shifters and junction box is as easy as plugging them in and riding your bike. All you need to do is determine the length you need for your bike.