This item has Built-in Amplifier, Multi Function, and USB Power. So it can be played for MP3, DVD, Computer, Walkman and so on. You can change the picture and choose frame at will Specification 1. Impedance: 4Ω 2. Frequency response: 20Hz - 18KHz 3. Power output: 5W 4. Power requirement: DC 3.0V (2 x AA batteries) 5. Sensitivity: 95Db