Digital Integrated Intelligence. The eagerly awaited Shimano Di 2 (Digital Integrated Intelligence) is here. Evolution never stops. This new technology brings shifting to a new level. It gives you a swift, definite shift every time & in every situation. Rigorously tested to perform in all weather conditions, for all riding styles & terrain. Key Feature The power house of Dura-Ace Di 2 is a long-life 7.4V Li-Ion battery that is both compact & reliable, taking shifting effort away from you. Excellent sealing & reliability have been proven through repeated field tests in various riding conditions, including extreme temperatures, rain, mud, & cobble stone roads. Using a hard wired battery system which is both light weight & accurate compared to current wireless technology (as a wireless system would require 4 batteries: one for the RD, one for the FD, & one for each shift lever). The use of a single small & discreet battery is light weight, efficient & creates a robust & reliable system. One charge can give between 1000 & 2000 (around 1200 miles) kilometre range depending on conditions & front derailleur operation (as this is the main power drain). Reliable & secure water resistant connectors. Easily removable for charging. Weight: 68g (Manufacturer claimed)