The HP ZBook Fury 15.6 inch G8 Mobile Workstation Comes in 2 Different Drive Configurations and Supports up to 4 Drives. (One 2.5" Drive and/or Two M.2 NGFF (2280) Solid State Drives) or (Four M.2 NGFF (2280) Solid State Drives) Note: When the 3rd and 4th M.2 Drives are installed, they occupy the 2.5" Drive bay using a M.2 Drive holder adapter bracket p/n M22793-001. When the 2.5" Drive is installed, the 2.5" Drive covers the 3rd and 4th M.2 Drive slots. If the 2.5" Drive was not Installed from HP, you will need the 2.5" Drive bracket p/n M17041-001 and cable p/n M17062-001 for installation. (All 4 M.2 slots support PCIe NVMe Solid State Drives and run at Generation 3.0 x4 speeds)