These are my personal PS2 memory cards from back in the day. These were all confirmed as functional last year when a friend visited.

2 Sony OEM clear red ones and 3 Sony OEM black ones

I'm tossing in the Madcatz one for free. It works as well - I just always used it as a "backup" card since it isn't one of the OEM ones and now you can as well!

I don't have a PS2 anymore so while these come with a lot of sentimental value, I can't really justify having them around the house anymore.