A portable USB device with an improved configuration is described herein. According to one embodiment, a portable USB device includes a core unit having a USB plug connector coupled to one or more flash memory devices and a flash controller disposed therein, where the flash controller is capable of exchanging data with a host via the USB plug connector using a bulk-only-transfer protocol. The portable USB device further includes a housing for enclosing the core unit, including a front end opening to allow the USB plug connector to be deployed. The portable USB device further includes a core unit carrier for carrying the core unit for deploying and retracting the core unit, including a slide button to allow a finger of a user to slide the USB plug connector of the core unit in and out of the housing via the front end opening of the housing.