RTIV435DCSR5 RAID Tower IV (black color) with 1 4X1 eSATA/USB 2.0 Hardware Port Multiplier installed. Install up to four 3.5" SATA hard drives of any capacity (drives not included). Drives are installed onto drive enclosures that can be 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 FAST2 (2 drive RAID 0 Striping), SAFE2 (2 drives RAID1 Mirroring), BIG 2 (2 drives Concatenation), 3 drives in RAID 3, or 3 drives in RAID 5. RAID setting via a rotary switch on the back. OS independent, can be used on any system. RAID diagnostic via LED lights. Can install 3.5" IDE hard drive using optional Diamond IDE drive enclosure. 2.5" SATA or IDE hard drives can also be install with optional bracket and connector adapter.