The Shimano E-Tube SM-BMR1-L battery mount is the long battery mount that attaches to the water bottle mount. The long mount can also be modified to work on a 40mm Di2 specific battery mount. Battery sold separately. Use this mount for an external battery mounted to a bottle cage mount on a frameset with a port for internal wiring. E-Tube compatible so it works with Dura-Ace 9070, Ultegra 6870 and Ultegra 6770.