product description: support MP3 , automatically play, play the status of the red LED . support U disk (tested over 32G), TF card (tested 16G) playback mode; 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, please refer to the key operation instructions. button to adjust the up and track switch, volume + -, pause / play, mode switch, Note: "long press" time about 2S If you U disk mode, the proposed 5V supply, some U disk does not support 3.7V supply. Product specifications supply range: 3.7 ~ 5.5V Product Size: 45mm * 36mm Exquisite double board design, area copper, stable and reliable. Anti-static bag refined packaging, to avoid damage to the way of delivery static . Material: metal colour: blue Package Include: 1 x Mp3 lossless decode board Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.