We love the reliability, customization, and shifting precision offered by a wired Di2 setup. Every once in a while during a bike build or gruppo swap between frames, we'll run into a Di2 wire that comes up just a little too short. The EW-JC200 is a female-to-female junction box that allows connection of two Di2 wires to extend their length by around 31mm. Sometimes this is also necessary when working with bigger frames, tandems, or for complex routing of add-on shifters. The Di2 EW-JC200 is compatible with Shimano's E-tube Di2 systems.