Internal high quality Bluetooth module Small distortion supplies clearer 2.1 channel, stronger and more powerful sound Made of lightweight aluminum, it is portable with overload, short circuit, overheat protection Using high quality operational amplifier NE5532 (made in Mexico) to provide ±voltage source, German WIMA and Japanese ELNA capacitors, British CSR BT chip, American MAXIM professional headphone amplifier, the sound is transparent and smooth