Feature:   Onboard 2W mono amplifier (5V power supply up to 3W) can directly connected speakers (recommended with 4Ω3W speakers), 3.5mm gold-plated headphone jack can be accessed by headphones or external audio.  With MicroUSB power supply interface, using mobile bank power or USB charger power supply, can also be used 3.7V lithium battery, USB 5V power supply.  Support TF card (mobile phone memory card), U disk playback mode.  With a speaker terminal without soldering, easy wiring.     1) Support MP3 format, power automatically play, led status turn to red.  2) Support U disk (tested with 32G), TF card (tested with 16G) playing 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.     Key operation instructions:  "Prev / V--" key: "short press" to switch "Previous" song, "long press" to switch "volume down".  "Next / v ++" key: "short press" to switch "next song", "long press" to switch "volume increase".  "P / P / Mode" key: "short press" to "play / pause" switch, "long press" for the U disk, TF card "mode" select.  "Repeat" key: "short press" for the "single / full song" cycle switch (no long press function).     Note:  1. Long press time about 2S.  2. If you use U disk mode, the recommended 5V power supply, some U disk does not support 3.7V power supply.     Specifications:  Power supply range: 3.7 - 5.5V.  Product size: 45mm * 36mm.     Package includes:  10 x MP3 Lossless Decoder Board