4-5 inch air filters promote better airflow while reducing strain on the HVAC system, leading to improved efficiency and a longer lifespan for the system. These filters typically last longer than 1 inch or 2 inch filters, reducing the frequency of replacements and providing greater cost-effectiveness. They are ideal for households or businesses with higher air quality demands, such as those with allergy sufferers or sensitive individuals. While they may not be compatible with all HVAC systems, when they are, 4-5 inch air filters deliver optimal filtration and performance.