The battery forms the Di2's heart. Its lithium ion technology guarantees a range of at least 2,000km [1,250 miles] after which it can be fully recharged in just ninety minutes. The battery's status can be read from an indicator next to the handlebars so that you'll never be confronted with any unpleasant surprises. Derailleurs can also be reset or trimmed from this control unit.
External mounts are for external cables External cable sets are for upgrading your current bike to Ultegra Di2 cable routing
Internal mounts are for Internal cables that are compatible with frames specifically designed for Di2
A 2 year warranty is offered with all Shimano products from Chain Reaction Cycles (3 years on Dura-Ace and XTR products).
Buy Shimano Components from Chain Reaction Cycles, the World's Largest Online Bike Store.