1. Number of Audio Channels: Stereo(L+R) 2. Digital audio output: Coaxial output 3. Support audio file: MP3 Playback:MPEG1/MPEG2.5-extension layer3; MP2 Play Back:MPEG1 layer2 only; WMA play back :MPEG1 layer3 4. Support video format: MPEG4 simple compliate,D1 resolution(720X576) ; AVI(divx 3.11 4.0 5.0 Xvid) 5. Support Image: JPEG 6. I/O interface: Input port(USB 2.0 ,DC In),output port: A/V out, VGA out. 7. Power adapter:5V 2A DC adapter. 8. HDD-128 and HDD129 are designed for playing 3.5 inch hard disk with same function but different shape. HDD-108 is designed for playing 2.5 inch hard disk with same function as HDD-128 and 129.