18" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Color_White actual front end outer dimensions

actual front end outer dimensions are approximately 22 5/8" width X 30 5/8" height

Actual Filter Size – 17 3/4"w x 5 3/4" x 1"

+ Product Details Size – 12"w X 8"h is the size for the duct opening measurement only

For 10" Round Duct Opening - Spiral or Flex

18" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Color_White actual front end outer dimensions+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 6" OR 6" X 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 8. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 17. 75" x 5. 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