The Alienware m15 R4 Laptop Supports up to 3 Drives. (Two M.2 NGFF (2280) or (2230) Solid State Drives and/or One M.2 NGFF (2230) Solid State Drive in the WWAN Slot) Note: In the two primary SSD slots, the M.2 2230 Drive uses a adapter bracket and heat shield to accommodate for the larger M.2 2280 slot. If Installing a M.2 2280 Drive, you will need the M.2 2280 thermal heatsink cooling bracket p/n 0RT4G1 for installation. (M.2 slot-1 (SSD1) and slot-2 (SSD2) support M.2 2280 or 2230 Drives - M.2 slot-3 (SSD3)/WWAN slot supports M.2 2230 Drives only)