"Hi,
The fan slot is of 180mm size, so a 120mm filter will not cover all of it. We unfortunately don't have such a filter in our own product lineup, and I'm not sure if there are 180mm filters of other brands available in shops. However, if you use the fan slot to push air out of the case, dust should not be a problem.
As for a revision of the case; we are always looking for ways to improve and update our cases. Currently we are working on designing a windowed side panel for the Arc Midi, although we are still in the development stage of this project so it's very difficult to predict when it will be ready.
Best regards,
Fractal Design"