3C card can be used as traditional USB Disk -------3C card can be used as Standard SD/MMC card; it is the standard SD/MMC size. and it is DC/mobile/PDA media card also; 棗桽tandard SD/MMC and USB port; share storage media 棗桽tandard SD/MMC size; 棗梠nly 2.1mm , the Most thinnest Pen drive in the world, can be stored in wallet!