There was a time when if you bought a USB mouse, in the box was also ... it may well have come with an adapter for a 9-pin RS232 serial port. Those mice from a decade or more ago would have ...

We know, you’ve already got a USB to serial adapter ... With the ability to be directly plugged into a RS-232 port, this adapter will certainly catch the eye of retrocomputer enthusiasts.

Add or Remove Programs entry for FTDI USB Serial Converter Drivers. This is a driver pack that allows USB ports to be used to connect to Serial bus devices with a USB - Serial adapter cable.