... 4.USB/SD 5.Two VHF wireless microphones AK15-304 15 Inch Outdoor Professional Audio Equipment AK15-305 PA speaker box ... . This is a really multi-function plastic loudspeaker.Features:1.15 inch active speaker 2.With USB/SD/MMC Card player ... .Ideal for teaching ,tour guide system ,specch ,etc Amplifier Applicable Scope: *Room, outside(especially suitable dancing, gymnastics, demonstration's loud-speaker ...