Add 4 USB 2.0 ports to your low profile/small form factor computer through a PCI Express expansion slot. - 3 external USB 2.0 port - 1 internal USB 2.0 port - Low profile (SP bracket incl.) / Performance type and rate: USB 2.0, 480 Mb/s - OS compatibility: Windows 2000, XP (32/64-bit), Server 2003 (32/64-bit), Server 2008 R2, Vista (32/64-bit), 7 (32/64-bit), 8 (32/64-bit); Mac OS X (tested up to 10.8)