Nimitz 2ND HDD SSD Hard Drive Caddy For Dell Alienware M15x M17x Add a 2nd drive to your Alienware laptop by replacing your optical drive Works in optical drive bay of Dell Alienware 17 18, M15x M17x M18x Works with 2.5" SATA drives with heights equal to or less than 12.7mm (also compatible with 9.5mm HDD or SSD) Mounting screw-holes on caddy provided so you can transfer your original optical drive's mounting brackets to the caddy