The Return Grille Filter is a high-efficiency, long-life replacement. It captures a significant amount of the airborne particles in the air. Mounts in most third-party return filter grilles. Provides high-efficiency alternative to one-inch filter. Easy installation.Minimum Efficiency Reporting Value (MERV): 10
Replacement Schedule: Replace FC40R every 12 months or more often if filter appears dirty enough to block airflow through heating/ cooling system.