But let me share I've used hundreds of this model -> http://serialio.com/products/adaptors/usb_serial.php (the standard unit.)
It's quite odd to find Wacom selling serial port devices, in fact I didn't see that on their site. Too bad the story and model number is missing but I can write the standard model I noted is great for serial port work. You can find that adapter at Newegg and Amazon as well.
Bob
I have an Wacom Intuos Graphics Tablet with a serial port connecting cable, but I have not serial port on my computer. What kind of Serial port to USB adapter can I use to connect the tablet to my computer? The operation system is Word 7.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic