Drobo mini: Direct Attached Storage - 4 bay array - USB3 and Thunderbolt ports with 4 x 256GB SSD (DR-MINI-1A21-1TB) Portable RAID Holds 4 x 2.5-inch SATA I/II/III Drives; Includes 4 x 256GB SSD Holds 1 x mSATA SSD 2 x Thunderbolt and 1 x USB 3.0 Includes USB 3.0 Cable (Thunderbolt Cable Not Included) Hot Swappable Drives Any Drive/Manufacturer/Speed/Spindle Battery Backup