A portable memory storage device with a miniaturized memory storage assembly package with electrical contacts that further includes a casing, the casing holding the memory package and having a first end portion, a cover, the cover being rotatable about the first end portion of the casing, and at least a plug for engaging the cover and the casing and being fitted about the first end portion of the casing. When the cover is rotated about the first end portion of the casing to selectively cover or expose the electrical contacts, the plug rotates about the first end portion with the cover. Further, the first end portion includes a groove on an interior side surface, and when the cover is at a first locked state, a projection of the plug abuts against a side of the groove. The electrical contacts can be formed in accordance with the USB Specification.