The Dell 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 RT4G1 for installation. (M.2 slot 1 SSD#1 and slot 2 SSD#2 support M.2 (2280) or (2230) Drives - slot 3 SSD#3/WWAN supports M.2 (2230) Drives only)