Super sound quality, onboard 2W mono amplifier (5V power supply up to 3W) directly connected to the speaker (recommended with 4 ohm 3W speaker), 3.5mm gold-plated headphone jack can be connected to headphones or external audio. With Micro-USB power supply interface, it can be powered by mobile power supply or USB charger through the mobile phone data cable. It can also use 3.7V lithium battery and USB 5V power supply. Support TF card (mobile phone storage card), U disk playback mode;There is no need for welding with horn terminal, which is convenient for wiring;Modular design is easy to modify. :1. Support MP3 format, auto play when power on, red LED indicator is updated when playing;2. Support U disk (tested 32G), TF card (tested 16G) playback mode; power on default TF card mode, if there is no TF card 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 for details. 3. The buttons can adjust the up and down track switching, volume +-, pause / play, mode switching, please see the button operation instructions for details;4. You can press the button to set the "single / full song" cycle, the default is the full song cycle at power-on, press the "Repeat" key to change the cycle mode 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 x 36mm Package Contents: 4 x mp3 decoding module Note: 1. "Long press" time