Shimano BM-DN100-L Di2 Long Size Battery Mount Description: Shimano Di2 External Battery Mounts are intended for use with Shimano SM-BTR1 External Batteries when setting up Bluetooth shifting solutions. Features: All Di2 components on the bicycle require the same firmware version. Using Di2 components with different firmware versions may cause malfunctions Use Di2 system checker to update component firmware from http://e-tubeproject.shimano.com/