The Soler & Palau 990761 MERV-13 Filter is a replacement air filter supplied in a convenient 10-pack for TR90 and TR90G Energy Recovery Ventilators (ERVs). It works by filtering incoming ventilation air, capturing fine airborne particles before air passes through the ERV core and into the occupied space. The MERV-13 rating provides enhanced filtration compared with the standard MERV-8... https://www.partshnc.com/soler-palau-990761-filter-merv-13-tr90-90g-erv-10-pack