Fits well with the OEM filter. It only has to be pulled into position. In contrast, the eBay filter seems flimsy and may even rattle.
Although air would likely leave through the filter's left and right sides, it appears that the fan, which is depicted as a round component in the photographs, is drawing air through the filter's center. Without getting too technical, I personally like it when the filter fits snugly inside the fan. (for example, the original equipment manufacturer's filter made by Kia).
There is filth all over the surface of the old OEM filter, not just the circular area above the fan, and it has to be replaced.
I suppose I have now provided an answer to my own query. Nothing beats a tight fit!