The Dell Inspiron 15-3510 Laptop Supports Either 1 or 2 Drives Depending on the Battery Installed. (One 2.5" Solid State Drive or Hard Drive with the Smaller 3-cell 41Whr Battery Installed and/or One M.2 NGFF (2280) or (2230) Solid State Drive) or (One M.2 NGFF (2280) or (2230) Solid State Drive with the Larger 4-cell 54Whr Battery Installed) Note: Models that have the larger 4-cell 54Whr battery installed do not Support 2.5" Drives due to the larger battery occupying the 2.5" Drive bay. If the 2.5" Drive was not installed from Dell in models with the smaller 41Whr battery installed, you will need the 2.5" Drive caddy p/n VRFHK and cable p/n JW93P for installation. The M.2 (2280) and (2230) Drives use different thermal support brackets and cannot be interchanged. If installing a M.2 (2280) Drive, you will need the M.2 (2280) thermal support bracket p/n 0FP8R3 for installation. If installing a M.2 (2230) Drive, you will need the M.2 (2230) thermal support bracket p/n 037Y7P for installation. (The M.2 slot supports PCIe NVMe 3.0 x4 Solid State Drives)