The HP EliteBook 820 G3 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) Note: When the M.2 (2280) Drive is installed, the M.2 Drive occupies the 2.5" Drive bay. When the 2.5" Drive is installed, the 2.5" Drive covers the M.2 Drive slot. If replacing the M.2 Drive for a 2.5" Drive, you will need the 2.5" Drive bracket p/n 821665-001 for installation. (The M.2 slot supports SATA and PCIe NVMe Solid State Drives)