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, 1.41 oz (40 g), 1.5" (38 mm), 6.89" (175 mm), 5.43" (138 mm)