I purchased one 140mm dustfilter for evaluation. I was thinking it would be convenient to be able to easily remove the mesh filter for weekly cleaning. The four tiny screws used to attach the mesh filter to the filter's the outer plastic frame seemed like a good idea. I attached the dust filter to a Lian Li 140mm fan. I immediately saw a problem. The diameter of the mesh filter was not large enough to form a seal around the 140mm fan. There was a small open gap all the way around the outer edge of the mesh. The gap allowed unfiltered air to enter the case.
I also went to our local computer shop and checked Corsair, Fractal Design, Silverstone, and Thermaltake 140mm fans. The open air gap around the outer edge of the mesh filter was present for all of the fans. This suggests the diameter of the mesh filter is a little bit off.
On the positive side the 140mm filter might work quite well with 120mm case fans. The filter would extend beyond the 120mm fan hole. In addition there is sufficient clearance to attach the filter directly to a case panel. The mounting screws would not interfere with the frame of a 120mm fan.