The HP ZBook 15 G5 Mobile Workstation Supports up to 3 Drives. (One 2.5" Solid State Drive or Hard Drive and/or Two M.2 NGFF (2280) Solid State Drives) Note: If the 2.5" Drive was not installed from HP, you will need the 2.5" Drive bracket p/n L28721-001 for installation. (Both M.2 slots support SATA and PCIe NVMe Solid State Drives)