Based on this product's specifications, here are some alternatives and similar models
Expansion Card DeLOCK PCI Express x1 to 2 x Serial RS-232
Summary description:
The DeLOCK PCI Express x1 Card provides two RS-232 serial ports, supporting various data bits and stop bits configurations. With a FIFO buffer of 256 B, it ensures efficient data handling. Compatible with Windows 10 and 8.1, this card is ideal for expanding connectivity options in your system. Compact design with dimensions of 45 mm width and 64 mm depth makes it suitable for various setups.