NOTE:(VERY IMPORTANT!!!)1.It must connect a 7.4V lithium battery to open.---this is very important for power on.2.Because national delivery regualtion,the battery not included.3.The positive and negative poles of the battery must be connected according to the this picture, otherwise the board will be burnt.Features:1.Support reading MP3 music in U disk and TF card2.Built-in Bluetooth receiving function, can receive Bluetooth music from mobile phones;3.For 7.4V lithium battery, can be charged with DC9V/1-3A charger;4.With AUX IN external audio input function, can be connected to the computer to play;5.The panel has a wired jack, which can be used to sing or sing:6.Rated power 40W, peak 60W;7.Size: 190*85MMPackage included:1* 7.4V Bluetooth Amplifier board (Without Battery)2* SPeaker Wires1*Remote Control(Optional)