Calfee Designs Shimano Di2 Internal Seatpost Battery + Wiring Harness & Charger: 7.4V Lithium
This battery setup is designed as an upgrade in weight and performance from the stock Shimano equipment. Included is the Calfee Design battery, charger/cable, wiring harness, and some clips. I do not have any experience with this setup and cannot confirm it is a complete set.
This set has not been tested, but I was told from the previous owner it works well with low miles. I can see that a blue wire is cut in the wiring harness that goes to the battery. Sold AS-IS, with no returns.