The Dell Precision 15-3540 Mobile Workstation Supports a Single Drive Configuration and is Available in Two Variants from Dell. (Variant 1 - One 2.5" Hard Drive or Solid State Drive) or (Variant 2 - One M.2 (2280) or (2230) Solid State Drive) Note: The M.2 2280 / 2230 drives and the 2.5" drives are both installed in the same location using different drive brackets. The M.2 2230 drive uses a extender bracket p/n 07HMH to accommodate for the larger M.2 slots form factor. The M.2 2280 and 2230 drives require mounting bracket p/n 0KJK50 for installation. The 2.5" drives require caddy p/n 05P11T and cable p/n 0XY5F7 for installation.