SHIMANO BT-DN110A-7 Built-In Type Di2 Internal Battery The Shimano BT-DN110-A Built-In Type Di2 Battery is the power source for Shimano's 11 speed Di2 derailleurs and shifters. Its thin, sleek profile allows the battery to fit in seatposts or frames for a clean look. Compatible with EW-SD50 Di2 Wire SD50 connection port Waterproof design Compatible with SM-BCR2 charger Battery Chemistry: Li-Ion Rated Voltage: 7.4V Rated Capacity: 0.5 Ah / 3.7Wh Port: SD50 Weight: 51g Original Shimano parts guarantee that all components work perfectly for optimum performance and maximum safety and longevity.