14" x 36" or 36" x 14" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Compatible With Duct 6in actual front end outer dimensions

actual front end outer dimensions are approximately 18 5/8" width X 18 5/8" height

Actual Filter Size – 7 3/4"w x 15 3/4" x 1"

5" - SEE BELOW IN DESCRIPTION HOW TO MEASURE A GRILLE

12" Diameter Is The Size For The Duct Opening Measurement Only

+ Product Details Size - 6"w X 20"h is the size for the duct opening measurement only

14" x 36" or 36" x 14" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Compatible With Duct 6in actual front end outer dimensions+ Product Details Perfect Fit & Easy Sizing Designed for a 14" x 36" OR 36" X 14" duct opening (measured at the opening), with actual outer dimensions of 16. 5" W x 38. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 13. 75" x 35. 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