support MP3 format, 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, please 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: 45x 36mm Anti-static bag refined packaging, to avoid damage to the way of delivery static electricity. Material: metal+PCB colour: blue Exquisite double-layer board design, large area copper plating, stable and reliable. Package Contents: 2 * mp3 decoding module Note: 1. "Long press" time is about 2S 2. If you use U disk mode, 5V power supply is recommended, some U disks do not support 3.7V power supply.