The 313 MERV 13 Air Filter helps capture and remove common airborne contaminants and allergy triggers. This replacement air filter is 4 in. thick with a large surface area for capturing pollutants and offering superior filtration to typical 1 in. filters. Filtering out airborne contaminants helps clean the air you breathe and can lower the frequency of cleaning and vacuuming by reducing dust buildup around the house. It also maximizes the lifespan of your heating and cooling systems, which can become inefficient with dust and particle buildup. Patented AprilAire Self-Seal Technology reduces the amount of air bypassing the filter, helping deliver precise filtration of the air circulating in your home. This MERV 13 Air Filter is easy to swap out thanks to the AprilAire Pure Fit Promise and patented Interlock Rail System that lets the filter slide right into place. Contaminants removed based on air passing through the filtering system; Performance tested to ASHRAE 52.2; Standard, minimum efficiency reporting value MERV 13.