Surveyour 2.0 compact stereo speakers with built-in amplifier. It provides good sound quality and music clarity in a compact shape. It's perfect value-to-price product, which offers good performance at affordable cost. Tech spec:Input Voltage: 5V DC (USB PLUG)Loudspeaker Output Power :3W * 2 RMS Power supply : USB port Frequency : 90Hz- 20kHz Input Resistance : 4 OhmWorks well with: Laptops / Notebooks/ Netbooks and when using external power source (e.g. power bank) they can be used with MP3 players / Mobile Phones / Smartphones, tablets, etc Size of 1 speaker: 62 x 62 x 54mm