The External junction box A SM-EW90 used to be the junction box everyone had on their bikes. DURA-ACE 9150 introduced the EW-RS910 junction A, which has been the go-t0 junction box for any new bike since then.
While it is available in a 3 and 5-port version, the latter is rarely used and most people seem to opt for the 3-port version of the junction box.
You could replace this junction with the mountain bike System Information Display (XT SC-M800 | XTR SC-M9051), if you wanted to. This Information Display functions as a Junction A with three e-Tube ports, a display and features Bluetooth/ANT+ connectivity.
Details & specifications
|Shimano model code||SM-EW90-A (3-ports), SM-EW90-B (5-ports)|
|Shimano model name||External/Cockpit Junction A|
|Series||Ultegra 6770, Ultegra 6780, Ultegra R8000, DURA-ACE 9070, DURA-ACE R9150|
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