The HP ProBook 455 G4 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) 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 911705-001. If replacing the M.2 Drive for a 2.5" Drive, you will need the 2.5" Drive cover p/n 905771-001 for installation. (The M.2 Drive bracket supports SATA only Solid State Drives)