14" x 22" or 22" x 14" Cube Core Eggcrate Return Air Filter Grille for 1" Filter fixed bar + Product Details Size –

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

even without needing to remove the thermostat

but still very thin

Example: If your hole is 20" wide by 14" tall

14" x 22" or 22" x 14" Cube Core Eggcrate Return Air Filter Grille for 1" Filter fixed bar + Product Details Size –+ Product Details Perfect Fit & Easy Sizing Designed for a 14" x 22" OR 22" X 14" duct opening (measured at the opening), with actual outer dimensions of 16. 5" W x 24. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 13. 75" x 21. 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