Leo, that's not making sense my friend, what you are doing is confusing the thickness of the panel with the slot , the two do not have to be related , you have a panel and there are any panels , they can be rubber, wire , poly , composite combination - but they all have an overall size and a type, they have a varying thickness - and they all have the same aperture as , it does not matter what the screen media is, dependant on  who you talk to they will all say that their 's is the best - but then there is the aperture size , the aperture size is usually a little SMALLER than what you want to screen - remember all screen media will wear and the aperture will turn larger - you slot size will be 8.8 x 12 - - not sure from where you got 8.8 but that is what the slot it , then you need to know , if the slot is with or against the flow  etc etc etc ,    quite simple actually   the choses screen media thickness will vary, and there is a rule on selection of screen media thickness selection, the slot is then applied and the thickness of the aperture through the media should not be more than the smallest aperture size usually or you will land up with blinding issues

The difference between the two slot sizes for each panel is the open area per square foot. You could use the open area as part of the description of the panels.