Shimano SM-BTR2 Di2 Internal Mount Battery For Dura-Ace 9070Shimano SM BTR2 Di2 Internal Mount Battery For Dura Ace 9070 This is the power house of Shimano Di2 is this 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. If you're worried about running out of juice on a ride, know that