The Shimano BT-DN300 Battery is a high-quality power source designed for use with Shimano's Di2 electronic shifting systems. Weighing just 50 grams, this lightweight battery offers reliable performance and long-lasting power for your electronic drivetrain. The BT-DN300 features a sleek and compact design, making it easy to install and conceal on your bike frame. With a capacity of 500mAh, this battery provides ample power for extended rides. It is compatible with both internal and external mounting options, offering versatility for various bike setups. The Shimano BT-DN300 Battery is a must-have accessory for cyclists looking to enhance their shifting experience with the latest electronic technology.