The power house of Shimano Di2 is a long-life 7.4V Li-Ion battery that is both compact and reliable, taking shifting effort away from you Excellent sealing and reliability have been proven through repeated field tests in various riding conditions, including extreme temperatures, rain, mud, and cobble stone roads The use of a single small and discreet internal battery is light weight, efficient and creates a robust and reliable system One charge gives a 1000 kilometre range depending on conditions and front mech operation (as this is the main power drain) 500 times rechargeable life Battery is to be mounted with seatpost or frame/fork manufactures hardware normally inside the seatpost or seat tube/fork steerer Reliable and secure water resistant SD300 E-tube terminals connection Charging is done via stem junction or handlebar display Battery weight is 50 grams