1. Support reading MP3 music in U disk and TF card. 2. Built-in Bluetooth receiving function, can receive Bluetooth music from mobile phones. 3. With AUX IN external audio input function, can be connected to the computer to play. 4. The product can be used on 4-5 inches speaker,with 15 watts speakers. 5. Support external 3.7V rechargeable battery, can be with DC5V charger; (3.7V rechargeable battery and charger not included). NOTE:VERY IMPORTANT!!! It must connect a 3.7V battery to open. this is very important for power on. Colour:Black Material:Iron+PCB Package Contents: 1 * Amp board(Not including 3.7V rechargeable battery) 1 * Remote control(Built-in battery) 1 * Speaker cable Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.