Portable 2.0 Mini USB Digital Speaker [V-02] Portable Speakers Easy to Carry Everywhere System Configuration USB 2.0 & USB 1.1 With Audio Output With Sound Card Supports Hot Plug & Play Specification Speakers Dimension & Impedence: 4-OHMS Output: 3W x 2 (THD) = 10% Frequency: 90Hz-20KHz Sensitivity: ≥ 70dB Distortion: ≤ 0.3%