1. USB interface: date transfer / charging.
2. Next key: short time pressing - next track, Long time pressing - fast forward.
3. (+): volume up.
4. (-): volume down.
5. Prev key: short time pressing - last track, long time pressing - fast back.
6. Display.
7. Recording key: press to record, save the recording contents.
8. Mode key: Play / Pause / Set up / Power on / Power off.
9. Speaker.
10. Microphone: recording microphone.
11. Multi-function button: volume button / menu button, when playing; long time pressing - can adjust
the volume, when pause; short time pressing - can set up.
12. Power button: power on (long time no using, switch the button to closing position).
13. SD card slot.
14. Earphone jack.
