Giant ISP/Vector/D-Fuse Seatpost Di2 Battery Holder - Wheel World Bike Shops - Road Bikes, Mountain Bikes, Bicycle Parts and Accessories. Parts & Bike Closeouts!
PRO Di2 Battery Holder Seatpost Di2 Built-in Battery Mounting Bracket For Seat Rail Mounting 27.2/28.6/30.9/31.6 - AliExpress
Di2 battery holder - Nex-Gen Sports
Di2 battery holder - Nex-Gen Sports
Shimano BM-DN100 Battery Mount for SM-BTR1 Di2 Battery-Pack | BIKE24
PRO Di2 Battery Holder | Pro Bikegear
Shimano Di2 Battery Mount for SM-Btr2 | Jenson USA