Shimano Dura-Ace Di2 internal wiring kits are designed to work only on frames intended to support Di2 internal wiring. This Shimano Dura-Ace 7970 Di2 EW-7975 Internal Wiring Kit has the long battery mount meaning it mounts to the water bottle braze-ons with the battery sitting below the water bottle. It internalizes all the wires and the junction box with only the battery mounting externally.
This kit is used for Di2 framesets without a Di2 specific battery mount or if you just want to locate the battery on the downtube below the water bottle. Please don't hesitate to call with any questions regarding Di2 internal wiring. Questions we will ask will be regarding the location of the battery and junction box.