Product description: 
1) Support MP3 format, playing power on automatically, playing state red LED indicator update. 
2) Support U disk (be tested by 32G), TF Card (be tested by 16G) play mode; power on default TF card mode, if the TF card does not exist automatically jump to the U disk, and two kinds of equipment are installed, you can manually set the playback mode, please look at the key operating instructions.
3)Keys can be adjusted up and down track switch, volume + -, pause / play, mode switching, for details please see the key operating instructions.
4) Can be set button single /whole song ," default power up the whole song cycle, replacing the circulating mode by pressing the "Repeat" key. 

Key operating instructions:
The "Prev/V--" key : " short press "is switching to"the last song ,"long press" is for "volume decreasing"
The "Next++" key : " short press "is switching to"the next song","long press"is for"volume increasing " 
The "P/P/Mode" key :"short press"is switching to "play / pause", " long press"is U disk and TF Card mode's selection 
The "Repeat" key :"short press" is switching cyclically "single / song" (no press function) 
Note:
1 "long press" time is about 2S. 
2 If you use U disk mode, some suggestions of 5V power supply, some U disk doesn’t support 3.7V power supply. 

Product specifications:
Power range: 3.7-5.5V 
Dimension: 45mm*36mm