Filter's airflow restriction is primarily a function of surface area and filtration medium layers. More surface area results in a better airflow and more filtra

Filter's airflow restriction is primarily a function of surface area and filtration medium layers. More surface area results in a better airflow and more filtration medium layers results in a worse airflow. To maximize surface area of a filter, you can get a thicker accordion filter. This will generally provide good airflow and filtration characreristics. Sorry about video links below, I liked them at chart times, so you don't have to watch the video to check out the summary. Here is an example of airflow restriction vs filter. Note that 4 inch Honeywell filter only provides small static pressure rise over no filter option: https://youtu.be/RkjRKIRva58?t=456 https://youtu.be/RkjRKIRva58?t=456 At the same time, same filter is 5th overall in large particle removal: https://youtu.be/RkjRKIRva58?t=661 https://youtu.be/RkjRKIRva58?t=661 Thicker filters cost more, but also last longer. General rule seems to be that when you double the filter thickness, time between replacements doubles as well.