... 89dBSpeaker Units : 3"bass+trebleFrequency Response: 40Hz-18kHzDescription1.Built-in USB and SD memory card function2.Support MP3 Music format3.Volume ... kinds of speaker,such as:speaker,mini speaker,portable speaker,USB speaker,2.1 muitimedia speaker,5.1 multimedia speaker.2 ... make professional speaker,mini speaker,SD card speaker,hifi speaker,USB speaker,5.1 multimedia speaker,2.1 multimedia speaker,2 ...