StarTech-com-PEX4S553-4-Port-Native-PCI-Express-RS232-Serial-Adapter-Card-StarTech-com-PEX4S553-P-The-PEX4S553-4-Port-Native-PCI-Express-RS232-Serial-Adaptor-Card-with-16550-UART-from-StarTech-com-lets-you-add-4-RS232-DB9-serial-ports-using-a-single-PCI-Express-expansion-slot-P-P-Based-on-a-single-chip-design-this-4-port-serial-adaptor-card-allows-you-to-harness-the-full-capability-offered-by-PCI-Express-PCIe-while-reducing-the-load-applied-to-the-CPU-by-as-much-as-48-over-conventi