BM-DN100-S, Battery Mount for EW-SD50, Short, for External

SHIMANO BM-DN100-S Di2 Battery Mount Internal/External Routing

Di2 Battery Bt-dn110/dn300 For Dura Ace Ultegra Xtr Alfine

Shimano Di2 BM-DN100-S Battery Mount short internal/external

Pro Di2 Internal Battery Holder for Fork Steerer

Shimano Di2 BM-DN100-S Battery Mount (Short Size

Shimano SM-PCE02 Setting Kit for STePS and Di2 - AliExpress

Shimano Di2 BM-DN100-L Battery Mount long external routing

The 2nd generation Di2 e-Tube wiring system from Shimano has the SD300 designation. These wires and connectors are thinner than the SD50 generation. if you need to join two wires to one (3 total wires), or two pairs of SD300 wires to create a longer length for both pairs (4 total wires), you will need this EW-JC304 Di2 SD300 4-Port Junction Box.

Shimano EW-JC304 Di2 SD300 4-Port Junction Box

The Shimano Di2 BM-DN100 External Battery Mount - Long allows for mounting the BT-DN110 battery to the frame's water bottle cage mounts with external wiring. The mount allows for wireless communication with the EW-WU101 wireless data transmitter unit and Bluetooth components. Battery sold separately.

Shimano BMDN100 Di2 Long Battery Mount for External Wiring

Shimano SM-BMR2 E-Tube Di2 Battery Mount External Long

Shimano Di2 Battery Mount BM-DN100 Short Internal/External Routing

Shimano BM-DN100 Battery Mount for SM-BTR1 Di2 Battery-Pack