The Shimano Y-cable junction Di2 EW-JC130 is a cable junction with junction B function, which must be used when using the internal junction box EW-RS910 (junction A). It has three E-Tube connectors and serves as a connection between the junction box and the STIs. EW-JC130 is available in three different versions, depending on the combination of cable lengths, but the individual cables cannot be shortened.
Shimano Ultegra R8050 Di2 E-TUBE Y-Connector Cable Junction Y-split Routing (EW-JC130-MM & EW-JC130-SM)
