... for HI-Fi system 1.Product Features *With USB / SD / AUX/ FM (AUX ,FM Optional)*Built in RTC ... USB memory) Switch order will be SD→AUX→FM→SD (if only have SD card ), the Switch order will be ... USB memory) Switch order will be SD→AUX→FM→SD (if only have SD card )PREV :Same functions as Previous ... the numbers in series . Mp3 Player Module,usb/sd,FM,remote LCD mp3 module,8GB amplifier mp3 player module ...