RTM435R5 - RAID Tower Mini (black color) with 4X1 eSATA/USB hardware Port Multiplier installed. Install up to four 3.5" SATA hard drives of any capacity (drives not included). Drives are mounted onto the tower chassis using screws. 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 (RAID1 Mirroring), SAFE FAST (RAID 1+0 Mirrored Stripped), BIG 2 (2 drives Concatenation), FAST4 (4 drive RAID 0 Striping), BIG 4(4 drives Concatenation), RAID 1+0, RAID 3+S, or RAID 5+S. RAID setting via a rotary switch on the back. OS independent, can be used on any system. RAID diagnostic via LED lights.