The StarTech.com ICUSB2321FIS 1-Port FTDI USB to Serial RS232 Adapter Cable with Optical Isolation converts an available USB 1.1 or 2.0 port into an RS232 DB9 port. This allows you to connect, monitor, and control your serial devices. The adapter features integrated optical isolation circuits and surge protection to safeguard sensitive control equipment from electrical damage, making it ideal for industrial serial devices. Its versatile FTDI chipset supports COM retention and offers compatibility across various operating systems, including Windows, Windows CE, Mac OS, and Linux, facilitating easy integration into mixed environments.