product support MP3 , power automatically play, play the status of the red LED update. support U disk (tested over 32G), TF card (tested 16G) playback mode; power default TF card mode, if the TF card does not exist automatically jump to U disk mode, and both devices are installed, you can manually Set the playback mode, refer to the key operation instructions. button to adjust the up and down track switch, volume + -, pause / play, mode switch, Note: "long press" time about 2S If you use U disk mode, the proposed 5V power supply, some U disk does not support 3.7V power supply. Product specifications Power supply range: 3.7 ~ 5.5V Product Size: 45mm * 36mm Exquisite double board design, area copper, stable and . Anti-static bag refined packaging, to avoid damage to the way of delivery static electricity. Material: metal colour: blue Package Include: 1 x Mp3 lossless decode board