Correction, it was an $18.99 + $8.00 shipping SinTech Adapter card.

Looks like I may have found a way to use a USB Mouse on my Ancient KeyStone PC KBD/Serial Mouse -> ADB Adapter!

I hope this real USB 2.0 to Serial RS232 converter adapter type A is bi-directional or at least USB -> RS232/485/422.

From the Cabling I'm SURE it goes the other way. :-/