By A Mystery Man Writer
2nd Choice. Further information in the product description.
Shimano BM-DN100 Battery Mount for SM-BTR1 Di2 Battery-Pack
In-depth guide on upgrading your old Di2 bike
Shimano Dura-Ace 7970 Rear Wire Kit - Components
Shimano Long Size Battery Mount For EW-SD50 Ultegra-DI2 SM-BMR1 w
Shimano XTR Di2 1 x 11 setup
Shimano Di2 Battery Mount BM-DN100 - bike-components
SHIMANO BM-DN100 Di2 Battery Mount : : Sports & Outdoors
SHIMANO XTR DI2 Battery Case
Shimano BMDN100 Di2 Long Battery Mount for External Wiring
Shimano Ultegra and Dura-Ace Di2 Electronic Shifting – Everything
Hands On Bike: Bike Friday HaD: Di2 Battery Placement and Wiring
Shimano Di2 BM-DN100-S Battery Mount short internal/external
Electronics - Lakeshore Bike