34" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 8" Diameter The operable dampers

The operable dampers

actual front end outer dimensions are approximately 28 5/8" width X 20 5/8" height

actual front end outer dimensions are approximately 12 5/8" width X 12 5/8" height

Actual Filter Size – 25 3/4"w x 17 3/4" x 1"

+ Product Details Size – 26"w X 34"h is the size for the duct opening measurement only

34" x 18" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 8" Diameter The operable dampers+ Product Details Perfect Fit & Easy Sizing Designed for a 34" x 18" Or 18" x 34" duct opening (measured at the opening), with actual outer dimensions of 36. 5" W x 20. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 33. 75" x 17. 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