A flash drive includes a main housing, a USB adapter unit mounted in the main housing and extending out of the main housing, an inner housing movably connected to the main housing, and a flash memory unit including a flash memory that is mounted in the inner housing, and a USB-A plug that is connected to the flash memory. The inner housing is operable to move, with respect to the main housing, between a USB-C position, where the USB-A plug is electrically connected to the USB adapter unit to allow for data transfer therebetween, and a USB-A position, where the USB-A plug is detached from the USB adapter unit to prevent data transfer therebetween, such that data is transferable to and from the flash memory via the USB-A plug.