... amplifer with USB/MMC 2.MP3,ipod,iphone,PC speaker 3.Built in battery and external battery slot 4.FM,LED display ... amplifier square box Description:1.Mini portable speaker audio amplifier built-in SD/MMC/USB drive,can read MP3 music format automaticly2 ... device, conect 3.5mm stereo audio cable between mini speaker socket "Line in" and other device, cell phone,MP3,MP4,PC,TV ...