We always buy this brand of air filter and generally always buy the least expensive one, which happens to be the "good" filter. I noticed a difference the first time we changed it out after moving into our house. The people that lived there before were using something else. With a very furry dog and cat I thought we would have to change out the filter more often but the recommended amount works out perfectly and our furnace is running better and more consistently than before. Plus my husband has allergies so we have to keep the house closed up and it makes such a difference. Once he is in the house in peak allergy season, he is fine.