2.0 active USB speaker for laptop PC, MP3, MP4,mellow and clear timbre, built-in acitve amplifier, Impedance: 4ohm, RMS: 3W+3W 2.0 active USB speaker for laptop PC, MP3, MP4,mellow and clear timbre, built-in acitve amplifier, Impedance: 4ohm, RMS: 3W+3W USB speaker, mp3 speaker, speaker