filter

Can anyone share their experience with these? Why is one of the filters smaller in the "internal" set? Is it because the filter isn't intended to go over the CPU area due to low clearance? Is it possible to use the "external" filters internally? If so, just how much clearance do you lose?

I'm just starting my A4 v3 build. I took the case out of the box last night and had a look at things. This will be an air-cooled build and I intend to install a 92mm fan in place of the 2.5" drive tray. Given that the tray is installed using screws through rubber grommets, the holes in the case...