... 2,professional amplifier,with USB,TF,MPS input 3,several colors to selection:pink,black,red,white, ... reach 15 hours ,Battery life can reach 2-3 yearsCooperate with wearing type microphoneAmplification effect is goodEasy to ... SourceLi-Polymer 3.7V x 2Li-Polymer 3.7V x 2Li-Polymer 3.7V x 2Li-Polymer 3.7V x ... ISO,CE,ROHS etc certificates Teacher, Guide Portable Voice Amplifier Megaphone HTY-G588 black