The Asus TP501UB Laptop Supports Single and Dual Drive Configurations. (One 2.5" Solid State Drive or Hard Drive and/or One M.2 NGFF (2280) Solid State Drive) Note: If the 2.5" Drive was not installed from Asus, you will need the 2.5" Drive caddy for installation. (The M.2 slot supports SATA only Solid State Drives)