36" x 26" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 14" Diameter accordion-item { margin-bottom: 16px

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our Circular Air Supply Valves are ideal for low and medium pressure ventilation air conditioning systems

With a 4" diameter for the duct opening measurement

+ Product Details Perfect Fit & Easy Sizing - Designed for a 20" x 36" OR 36" x 20" duct opening (measured at the opening)

36" x 26" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 14" Diameter accordion-item { margin-bottom: 16px+ Product Details Perfect Fit & Easy Sizing Designed for a 36" x 26" OR 26" x 36" duct opening (measured at the opening), with actual outer dimensions of 38. 5" W x 28. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 35. 75" x 25. 75" x 1" Premium Airflow Efficiency High performance cube core eggcrate design allows 95% airflow efficiency, reducing energy costs and maximizing HVAC system lifespan. Durable, Rust Free Aluminum