20" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 6" Round Duct Pipe + Product Details Size -

+ Product Details Size - 12" X 12" is the size for the duct opening measurement only

with actual outer dimensions of 20

+ Product Details Size - 10"w X 12"h is the size for the duct opening measurement only

this thermostat guard is compatible with most standard thermostat models

+ Product Details Perfect Fit & Easy Sizing - Designed for a 8" x 18" or 18" x 8" duct opening (measured at the opening)

20" x 6" Cube Core Eggcrate Return Air Filter Grille for 1" Filter 6" Round Duct Pipe + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 20" x 6" OR 6" x 20" duct opening (measured at the opening), with actual outer dimensions of 22. 5" W x 8. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 19. 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