The HP ProBook 640 G4 Notebook 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 HP, you will need the 2.5" Drive bracket p/n L09539-001 for installation. (The M.2 slot support SATA and PCIe NVMe Solid State Drives)