The HP ProBook 11 EE G1 Notebook Comes in 2 Different Drive Options from HP and Supports Single Drive Configuration Only. (One 2.5" Solid State Drive or Hard Drive) or (One M.2 NGFF (2280) Solid State Drive using a M.2 Drive Bracket and Connector Board) Note: When the M.2 (2280) Drive is installed, the M.2 Drive occupies the 2.5" Drive bay using a M.2 Drive bracket p/n 809859-001 and connector board p/n 811608-001. If replacing the M.2 Drive for a 2.5" Drive, you will need the 2.5" Drive hardware kit p/n 809858-001 (Includes: 2.5" Drive bracket and screws) for installation. (The M.2 Drive connector board supports SATA only Solid State Drives)