I have an unusual size, so buying on-line or calling to order is the easiest for me. I have cats. I vacuum weekly, dusting is optional as it doesn't seem to be dusty with these filters. I also find that replacing them is not as often as advised. Every 6 months for me. Living in California - use both air/heat but not as often as for most people around the country. For a reminder, I mark the date on the side of the filter before I install. My mom is allergic to cat dander and doesn't appear to have a problem when visiting. I attribute it to the filters.