Superior Quality Hard drive caddy, 12.7 mm Encouragement 2.5" SSD or SATA hard drive disk, 7mm or 12.7mm Encouragement Maximum Speed Up to 6 Gbps for SATA III, SATA II, and SATA I Encouragement Hot Swapping Idea: Add a second SATA HDD or SSD in place of your optical drive SuperDrive (DVD/CD-ROM).