Shimano Di2 12v 4-port internal connection box EW-JC304

(7 reviews)

Allows connection of Di2 12v cables

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Transmission type

Ref : 1870515

€37.39

Price : €49.99

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Based on 7 reviews

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Boitier interne connexion Shimano Di2 12v 4 ports EW-JC304

Shimano Di2 12v 4-port internal connection box EW-JC304

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Shimano Di2 12v 4-port internal connection box EW-JC304

€37.39

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With the same function as its 11-speed counterpart, this housing allows you to connect all SD300 generation Di2 cables.

Sylvain C.

Mechanical expert

The Shimano EW-JC304 4-port connection box is a component of the Di2 12-speed group. It allows you to connect the Di2 12v EW-SD300 cables internally.

This 4-port version allows you to connect both derailleurs and shift levers if you wish to connect them instead of using the wireless function.

Technical specifications- 12-speed Di2 transmission - 4 ports - Internal frame position - Compatible with Di2 EW-SD300 cables - Shimano reference IEWJC304

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10/10

Based on 7 reviews

Régis F.
Published Jun 20, 2026 at 03:57 pm (Order date: Jun 06, 2026)

5

Not used yet, in line with what I expected (Translated review)
SERGE A.
Published Jul 12, 2025 at 07:24 pm

5

Perfect for updating Shimano Di2 handles, by connecting the handles to the front derailleur. (Translated review)
Jean jacques F.
Published Apr 04, 2025 at 06:06 pm

5

easy to find on the site, good tracking and fast delivery (Translated review)
Isaac d.
Published Jan 28, 2025 at 05:40 pm

5

Allowed me to update my shifters. Perfect (Translated review)
Frederic C.
Published Jul 16, 2024 at 03:05 pm

5

Perfect and essential for updating the Shimano 9270 group. (Translated review)
Franck s.
Published Jun 01, 2024 at 10:52 pm

5

Bought to update the grips. Also plan for a slightly long DI2 cable. (Translated review)
Paul V.
Published May 22, 2022 at 10:12 am

5

Connection box that allows the connection of rear derailleur and shifters with an additional cable, for updating (the shifters). (Translated review)