... Pau,repeat,mode Decoder Board with FM radio for SD card,usbFunction and features: SD/MMC/USB Card MP3 Decoder Board, pcb board, ... to control external audio volume-Application: Ordinary audio combination, Car audio, multimedia speaker, subwoofer, amplifier, electronic products and ... +, ALARM+, and POWEROFF+.4.“MODE”: When this player works with SD card and USB flash drive together, it has such switching ...