The PEX1S553LP PCI Express Serial Card turns a PCI Express slot into an RS232 (DB9) serial connection. The card is constructed using a native single chip design that lets you harness the full capability offered by PCI Express (PCIe), while reducing the load applied to the CPU by as much as 48% over conventional bridge chip serial cards. The PCI Express RS232 Serial Adapter Card is compatible with a broad range of operating systems, including Windows and Linux Kernel 2.6.11 to 4.11.x, and ships with a low profile/half-height bracket installed, but includes an optional full profile bracket that lets you add a serial port to virtually any computer (regardless of the case form factor).