The double bass enhancement unit designed to enhance and optimize the speaker’s sound. Built-in 1800mAh rechargeable battery. Details: 10W Bass double horn, double bass diaphragm, clear treble. Wireless Bluetooth transmission distance up to 10 meters. Noise cancelling microphone. Battery lasting up to 12 hours. AUX audio line. USB play. 8.4'' X 3.5'' X 3.6''.