This Reznor rear filter rack assembly is designed to accommodate a 1-inch filter. It is compatible with unit heater models that have an airflow capacity of 400 to 800 CFM (cubic feet per minute). The assembly is intended for use in HVAC systems to ensure that air passing through the unit heater is adequately filtered. The product's dimensions and specific configuration are tailored to fit seamlessly with compatible Reznor unit heaters, facilitating ease of installation and maintenance.