Got it off ebay. Mostly CIB except doesn't have the PC Paint floppy but that was released as PD software a while back so it's not too hard to find online. Plugs into the serial port and draws power from the lightpen port. Comes with glass mousepad with gridlines on it so the mouse can see where it's going. LoL.
I've got one of the 3 button "normal" connector (as in can work on the regular PCs) and it's pretty nice. Otherwise identical except there's an AC adapter to power it.
I have since found a copy of PC Paint. I think the version is 1.09, so earlier than the PC Paint Plus I found earlier and what would likely have been included with the mouse package.
I obtained a 2 button version of this in a collection but without the ac adapter and mouse pad. Are these something I can replace with some sort of makeshift or generic part? I have some universal ac adapters but not sure on the voltage requirements and all with the adapter.