Feature Onboard 2W mono amplifier 5V power supply up to 3W can directly connected speakers recommended with 43W 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 downNext v key short press to switch next song long press to switch volume increaseP P Mode key short press to play pause switch long press for the U disk TF card mode selectRepeat key short press for the single full song cycle switch no long press function Note 1 Long press time about 2S2 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 5VProduct size 45mm 36mm Package includes 3 x MP3 Lossless Decoder Board