Hard to know exactly what a filter is doing until one pulls it out for replacement. So far seems like the filters are well made and hope they do the trick!
Purchased a pack of 5 18x24. Filters are approx. 1/2 inch short of the dimensions in my air vent and bow inwards when the A/C unit is running. I use masking tape to complete the seal. I'll go back to the Filtrete when the 5 are gone.