6" x 28" or 28" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 8.5" X 30.5"] w10h10 Actual Filter Size – 7

Actual Filter Size – 7 3/4"w x 29 3/4" x 1"

+ Product Details Size - 8"w X 14"h is the size for the duct opening measurement only

then you'll need a 14-inch round vent

+ Product Details Heavy-Duty Steel Construction - Made from 20-gauge steel for superior durability and reliable performance

+ Product Details Size - 20"w X 30"h is the size for the duct opening measurement only

6" x 28" or 28" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 8.5" X 30.5"] w10h10 Actual Filter Size – 7+ Product Details Perfect Fit & Easy Sizing Designed for a 6" x 30" or 30" x 6" duct opening (measured at the opening), with actual outer dimensions of 8. 5" W x 32. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 5. 75" x 29. 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 Made