Shimano Di2 SM-BMR2 Long Battery Mount Long version of Shimano Di2 SM-BMR2 Battery Mount. Meant for use with bottle cage mount Di2 systems and frames that don't feature designated Di2 battery mounts. This battery mount can be attached to water bottle mounts on the down tube or seat tube of your frame. Available in external and internal routing version, select the version that matches your wiring kit. Mounting hardware included.