Key operation instructions "Prev / V--" key: "Short press" is to switch "previous" song, "long press" is "decreasing volume" "Next / v ++" key: "Short press" is to switch "Next" song, "Long press" is "Volume increasing" "P / P / Mode" key: "Short press" for "play / pause" switch, "long press" for U disk, TF card "mode" selection "Repeat" key: "Short press", for "single / full song" cycle switching (no long press function) Product specifications Power supply range: 3.7 ~ 5.5V Exquisite double-layer board design, large area copper plating, stable and reliable. colour: blue Material: PCB size: 45 * 36mm Package Contents: 1 * 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. Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.