We're the owners of the site above and we were contacted by iDan (Thanks!) about this thread.
Thanks for all the positive comments about our items. We're glad you liked them.
Although IpadOne is correct about needing to have the actual device in hand for some cases, this was not the case for us with the iPad. There are various ways to determine the exact shape of the it, after all it probably was designed on a computer.
Unfortunately, we can't reveal the way our manufacturers correctly determined the dimensions for the iPad and cases, but if there was a problem we can guarantee that the customer will not lose in that situation.
Feel free to ask us any questions if you have any.
EDIT: Including Image