My disappointment was with the size of the filter. Silly me, I thought 4 inches meant 4 inches. No, in this case its only 3 5/8 inches. AND the filter I was replacing (also marked as 16x25x4) was actually 4 3/8. So the new filter was a bit loose in the filter receptacle. So, a warning. Check not only the marked size of the filter, but the ACTUAL size.
The filter's dimensions are way under the product listed size. It does not fit well in the AC return enclosure and I am left with a large gap. Useless product.Never again