It can record the volume into the microSD with changing the intensity of the LED light. Push the bottom,and you can also see the record by watching LED light changing.

1st push --- Start recording the volume. During recording(5 second),you can change the volume, and LED light will change accordingly.

 

2nd push --- Load the LED light changing that  you've just recorded.

 

3th push --- Waiting.

4th push --- same as 1st push.