The Asus Transformer Book R305LA Laptop Supports Single and Dual Drive Configurations. (One M.2 NGFF (2280) Solid State Drive in the Tablet and One 2.5" Hard Drive in the Keyboard Dock on Select Models) Note: The M.2 Drive in the tablet is upgradable. The 2.5" Drive is only supported in the keyboard dock on select models depending on the revision.