The Dell XPS 9520 Laptop Supports Single and Dual Drive Configurations. (Two M.2 NGFF (2280) or (2230) Solid State Drives) Note: The two M.2 slots use different thermal brackets. The primary M.2 slot (SSD-1) uses thermal bracket p/n 0130R6 and the secondary M.2 slot (SSD-2) uses thermal bracket p/n 04TW9C. The M.2 (2230) Drive uses a adapter bracket p/n 07HMH to accommodate for the larger M.2 (2280) slot. (Both M.2 slots support Generation 4.0 x4 and 3.0 x4 PCIe NVMe Solid State Drives)