PCI-E Express To 2 Ports SATA III (3.0) + 2 Ports eSATA Expansion Card 6 Gbps SFF Type: PCI Express to eSATA Card External Ports: eSATA x 2 Internal Ports: SATA x 2 Standard: SATA 3.0 and PCI-Express 2.0 compliant Data Transfer Rate: 6.0 Gbps Operating Systems Supported: Windows 2003, Windows XP, Vista, Windows 7 and 8 (32 and 64-bit). MAC OS 10.8 and 10.9 Compatibility: PCI Express x1, compatible with PCI-E x4; x8; x16 Specifications: SATA 3.0 and PCI-Express 2.0