I'll be that guy I guess then... they stated on their page that credit cards are 0.8mm while the muxcard is 1mm and yet they still claim it is "literally the size of a credit card"... not to mention that they carved out an NFC card, not a credit card.
Yes it's still impressive either way, I'm not debating that.
I did notice that difference too. But previous "credit card size" projects have all been several mm (as in couldn't fit a wallet designed for credit cards). So 1 mm is... pretty sweet!
It said that the specification states 0.8mm, but that many real world cards are thicker. Are credit cards actually 0.8mm?