36" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Material_Aluminum + Product Details Size –

+ Product Details Size – 20"w X 36"h is the size for the duct opening measurement only

+ Product Details Size - 25"w X 36"h is the size for the duct opening measurement only

Design – Unrestricted airflow for your HVAC system - adjustable one-way louver with full horizontal airflow directional control - single deflection supply grill with 96% airflow - noise free components - no vibrating louvers etc

+ Product Details Perfect Fit & Easy Sizing - Designed for a 20" x 16" OR 16" x 20" duct opening (measured at the opening)

+ Product Description Introducing the 6" Butterfly Damper – Your Solution for Controlled Airflow

36" x 8" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Material_Aluminum + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 36" x 8" OR 8" x 36" duct opening (measured at the opening), with actual outer dimensions of 38. 5" W x 10. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 35. 75" x 7. 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