The HP ZBook Studio x360 G5 Convertible Workstation Supports Either 2 or 3 Drives Depending on the Battery Installed. (One 2.5" Solid State Drive or Hard Drive with the Smaller 4-cell 64Whr Battery and/or Two M.2 NGFF (2280) Solid State Drives) or (Two M.2 NGFF (2280) Solid State Drives with the Larger 6-cell 95.6Whr Battery) Note: Models that have the larger 6-cell 95.6Whr battery installed do not support 2.5" Drives due to the larger battery occupying the 2.5" Drive bay. If installing a 2.5" Drive in models with the smaller 4-cell 64Whr battery installed, you will need the 2.5" Drive bracket p/n L28686-001 for installation. (Both M.2 slots support SATA and PCIe NVMe Solid State Drives)