... USB2.0 full-speed host controller(3)SD/MMC CARD controller(4)One route AUX input ... External power input or remote receiving window, but most of condition for remote receiver. 4,USB power ... other, AUX input, FM . Lasting press for 3 secondsRemote controller function1, MODE,Mode key, USB flash disks ... frequency in FM mode);numeric key, combined selection: for example ,if you want the thirteenth song, ...