... can release perfect sound3.built-in lithium batteries and USB -TO- DC connection which can be used conveniently; 4 ... .it can connect to MP3/MP4 player, cell phone ,notebook computer, ... built –in lithium batteries and USB-TO-DC 5.0V connection 5.It can connect to MP3/MP4 player, cell ... condition, the speaker will self regulate to its optimised state after leaving it on ...