... 3 Mini size big power waistband teaching tour guide speaker with Reverb/EchoFeatures*Mini size,easy to take*18W output power ... 3.7V/1100mAh Lithium Battery, convenient and environmental*Connect computer with USB data link, used as speaker*Built-in 3" high ... , Morning exercise, Training, Sports, Speech,Publication,Outdoor entertainment 2012 Belt Portable Mini Audio Amplifier Speaker with Reverb/Echo V-3