RTII525DAH RAID Tower II (black color) with 1 5X1 eSATA/USB 2.0 Hardware Port Multiplier installed. Install up to four 2,.5" SATA hard drives or SSD and one 3.5" SATA hard drives of any capacity. Drives are added or removed like tape cartridge from each drive bay. Connect to system via USB 2.0 or eSATA port (connecting cables included). Drives can be configured as FAST (RAID0 Striping), SAFE (RAID1 Mirroring), JBOD* (Just a Bunch Of Disks or individual drive), BIG (combined single volume), SAFE FAST (RAID 1+0 Mirror Stripped). RAID setting via software utility under Windows, Mac OS or Linux. OS independent, can be used on any system. RAID diagnostic software utility.