... is widely used at home, office , school , church , factory , hospital ,meeting , restaurant , army etc .Basic function: ... could hear amplified volum and enjoy it .2.USB/TF/MMC input : when you want to enjoy music ... , just plug in you USB(TF/MMC) to the amplifier slot and you will ... : 8-15 hours Function :louder speaker USB/ TF Card FM Radio MP3 input Song Switch This specification on ...