Add 4 RS232 serial ports to any PC using a single PCI Express expansion slotThe PEX4S553B 4-Port PCI Express Serial Card (with breakout cable) lets you add 4 RS232 serial ports using a single PCIe expansion slot, with an included 1-to-4 cable enabling you to add 4 serial ports to a single low profile slot.The serial card features a native single-chip design that provides optimum reliability and speed, reducing the CPU load by up to 48% over conventional bridge-chip serial cards - a cost-effective solution for connecting legacy serial devices to PCIe-enabled computers.The multi-port serial adapter includes both full profile and low profile/half-height brackets for compatibility with standard and small form factor computers, and is compatible with a broad range of operating systems, including Windows, Linux, and MAC OS.This product is a replacement for our PEX4S552B card.Backed by a StarTech.com lifetime warranty and free lifetime technical support.The StarTech.com Advantage- Lower CPU load of native single-chip, single lane PCI Express design ensures optimal system performance (up to 48% less CPU load)- Includes both standard and low profile/half-height brackets, which makes this the perfect card for any application, including small form factor embedded applications- Breakout cable design means that only one expansion slot is needed, to add 4 additional serial ports to any system