Compatible with Harman Kardon Onyx Studio, Onyx Studio 2 and Onyx Studio 3 Wireless Bluetooth Speaker. 3.7V 2600mAh Li-ion power battery with 3 prongs connector. Same voltage, same size compare with original battery. Professional Battery Management System (BMS) provides multiple protections for over-charge, over-discharge, short-circuit, over-voltage, over-current and over-heat. Battery size is 2.75'' long and 0.75'' diameter. Wrapped gasket on battery and wires to reduce noise and keep high quality sound. Make sure your speaker is Harman Kardon Onyx Studio, Onyx Studio 2 and Onyx Studio 3 before placing order to prevent buying wrong battery. Easy to install, 12 months warranty, local after sale team guaranteed 7/24 response to online messages. Compatible with Harman Kardon Onyx Studio, Onyx Studio 2 and Onyx Studio 3 Wireless Bluetooth Speaker. 3.7V 2600mAh Li-ion power battery, same voltage, same size compare with original battery. Professional Battery Management System (BMS) provides multiple protections for over-charge, over-discharge, short-circuit, over-voltage, over-current and over-heat.