PNY P-DSA2-PCIE-RF 2-Channel SATA II Raid PCIe Card Connect 2 SATA II hard drives to your computer ,This card supports data transfer rate of 300MB/second SATA II transfers at up to 2400Mbit/second versus USB 2.0 at 480 Mbit/second,Supports SATA hard disk hot-plugging Supports RAID 0, RAID 1, and Native Command Queing, 300MB/second is faster than USB, Firewire, or PATA Windows Vista compliant, also Windows 2000, Server 2003, and XP .The card has 4 connectors (2 internal and 2 external) RAID 0 is for striping and RAID 1 is for mirroring your hard drives