With the 4-Port PCI Express Serial Card (with breakout cable) PEX4S553B, you can add 4 serial RS232 ports through a single PCIe expansion slot. Thanks to the included 1-to-4 cable, you can add 4 serial ports via a single low-profile slot. The serial card features a native single-chip design for optimal reliability and speed while reducing CPU load by up to 48% compared to traditional serial bridge chip cards, making it a cost-effective solution for connecting older serial devices to PCIe-enabled computers. The serial multiport adapter comes with both standard and low-profile/half-height slot brackets for compatibility with standard and compact computers, and it is compatible with a variety of operating systems, including Windows, Linux, and Mac OS. This product is a replacement for our PEX4S552B card. It comes with a lifetime StarTech.com warranty and free technical support for the entire lifespan of the device.