Been using this filter for almost 7 years now. When my Heat Pumped was installed they accidently cut the filter hole in the top rather than the bottom. Rather than ask for a new door I had a second hole added to the bottom. Every month I put a new filter in the top and move that filter to the bottom. This gives me a two month life of filter and great airflow for electric energy usage. The yearly checkups have never had to clean the unit fan. As a widower I find it sees to be an extra house cleaner and keeping the house dusted is far more what a elder man needs. Well worth the cost for me.