StarTech.com PEX2S552B interface cards/adapter

"Add 2 RS232 serial ports to any PC using a single PCI Express expansion slot
The PEX2S552B 2 Port RS232 PCI Express Serial Card w/ Breakout Cable lets you add two RS232 serial ports using a single PCIe expansion slot. With the included ""break out"" cable, you can even add two ports to a single low profile slot.
The PCIe serial card features a native single chip design that provides optimum reliability and speed, while reducing the CPU load by as much as 48% over conventional serial cards that utilize a bridge chip for communication with the host PCI Express bus - a cost-effective solution for connecting legacy serial devices to modern PCIe-enabled computers.
The (x1) PCI Express Multiport Serial Adapter Card includes a full profile and low profile bracket to ensure compatibility with both standard and small form factor computers, and is compatible with a broad range of operating systems, including Windows® XP/2003/Vista/Windows 7/Server 2008 R2 (32 and 64 bit), Linux Kernel 2.6.11 and up, as well as MAC OS 10.5 and above.
Backed by a StarTech.com Lifetime warranty and free lifetime technical support."
" * Lower CPU load of native single-chip, single lane PCI Express design ensures optimal system performance
* Works for any style PC with both low and full profile brackets included
* Broad OS Support including 64-bit Windows Operating systems
* Only one expansion slot is needed to add two additional RS232 serial ports to any system"

StarTech.com PEX2S552B, ExpressCard, Black, 40 g, 38 mm, 175 mm, 138 mm