trading card thickness

What does "pt" represent in terms of thickness trading card?

I was looking Ultra Pro Magnetic cases some business cards, and have thicknesses of many, but I do not know what they mean (20 pt, 35 pt, 55 pt, 100 pt, etc) What is and how to say pt, 20 points compared to the thickness of a Magic Gathering card? Or a Pokemon card?

In typography, a point is the smallest unit of measurement a subdivision of larger pike. It is commonly abbreviated as pt. The traditional printer point, since the era of hot metal typesetting and presswork, varied between 0.18 and 0.4 mm depending on the various definitions of the feet. (% Http://en.wikipedia.org/wiki/Point_% 28typography 29)

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