Based on this product's specifications, here are some alternatives and similar models
4-port PCI Express RS232 Serial Adapter Card StarTech.com PEX4S953LP Low Profile
Summary description:
The StarTech.com 4-port PCI Express RS232 Serial Adapter Card features a PCIe interface, 16950 UART, and supports Windows and Linux. It provides reliable serial communication with a baud rate of 921.6 Kbit/s and a low profile design for compact installations.