Although I like & have to have this filter for my house HVAC system, I find that I am changing the filter every month NOT the 3 mos it is supposed to last. I did let one set go approx 45 days, but found the old filters collapsed into the vent due to the lack of air able to pass through. They do clean the air that passes thru, but definitely NOT for 3 months! I would seriously consider another filter if available, at least to have comparison...more to follow if I do find one/some.