18" x 26" or 26" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w36h36 } /* LIST SPACING */

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+ Product Details Size - 25"w X 30"h is the size for the duct opening measurement only

Design – These Supply Diffusers with integral round necks are recommended for heating

Actual Filter Size – 35 3/4"w x 7 3/4" x 1"

18" x 26" or 26" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w36h36 } /* LIST SPACING */+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 26" OR 26" x 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 28. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 17. 75" x 27. 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