CADT001SA2-B Hard Drive Array offers an unbeatable combination of RAID data protection, 3.0Gbit/sec eSATA speed and a vast storage capacity of 1TB (500GB mirrored) for your Mac. This dual-bay drive features swappable hard disks and a built-in RAID controller and arrives preconfigured in Spanning (BIG). The CADT-SA2 is easily configurable to RAID 1 to protect your important data if one drive fails, replace it with an identical drive and the data will automatically rebuild.