The Asus U303LAB Laptop Comes in 2 Different Drive Options from Asus and Supports Single Drive Configuration Only. (One 2.5" Solid State Drive or Hard Drive) or (One M.2 (2260) Solid State Drive using a Adapter Bracket with a M.2 Drive Converter Board) Note: When a M.2 (2260) Drive is Installed, the M.2 Drive occupies the 2.5" Drive bay using a converter bracket and board. If replacing the 2.5" Drive for a M.2 Drive, you will need the M.2 Drive converter bracket and board for installation. If replacing the M.2 Drive for a 2.5" Drive, you will need the 2.5" Drive caddy p/n 13NB04R1M01011 for installation. (The M.2 Drive converter board supports SATA Only Solid State Drives)