16" x 30" or 30" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 12in diameter these heavy-duty louvers are ideal

these heavy-duty louvers are ideal for use in attics

+ Product Details Size – 6" x 18" or 18" x 6" is the size for the duct opening measurement only

Actual Front End Outer Dimensions Are 14" Width X 5" Height - SEE IN DESCRIPTION HOW TO MEASURE A GRILLE

Actual Filter Size – 24 3/4"w x 35 3/4" x 1"

16" x 30" or 30" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 12in diameter these heavy-duty louvers are ideal+ Product Details Perfect Fit & Easy Sizing Designed for a 16" x 30" OR 30" X 16" duct opening (measured at the opening), with actual outer dimensions of 18. 5" W x 32. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 15. 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