The Filtrete furnace filter is designed to pull in and trap unwanted air particles while letting cleaner air flow through. It attracts and captures smoke, bacteria, viruses, household dust, and pollen. For maximum performance, it's recommended to replace your filter at least every 90 days. It's designed for residential use only. Using these filters helps to keep heating system return ducts clean and extend the life of the main furnace filter. For optimal performance, filters must be changed at least every 90 days. In fact, a dirty filter will slow down airflow and make the system work harder to keep you warm or cool, resulting in energy waste. Dimensions: 16 inches x 25 inches x 5 inches.