Shimano Di2 Batteries. Must purchase battery, charger, and power cable to complete the system

• 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/
• Di2 External Battery, battery charger, and power cable are universal between Dura-Ace 9070, 7970, Ultegra 6870, 6770 and Alfine Di2 systems
• Battery weighs 71g
• Shifter/Derailleur Compatibility:Dura-Ace 7970 Di2 , Dura-Ace 9070 Di2 , Shimano Ultegra Di2