iMicro Pure USB Digital USB2.0 Speaker System (Black) USB digital speaker Interface: USB 2.0 USB Power: 5V 500mA "Output: 3W (RMS) Speaker Unit: 2", 8 omh, 3W Control panel: soft switch volume; Up/Down and Mute Cable length: 3ft Frequency Range: 50Hz ~ 20KHz Certification: RoHS, CE