24" x 28" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Copper Coil-Insulated Line Set + Product Details Size -

+ Product Details Size - 28"w X 4"h is the size for the duct opening measurement only

+ Product Description Secure your thermostat with the heavy-duty Beige Metal Thermostat Guard

Premium Airflow Efficiency - High-performance cube core eggcrate design allows 95% airflow efficiency

+ Product Details Size – 18" x 28" or 28" x 18" is the size for the duct opening measurement only

24" x 28" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Copper Coil-Insulated Line Set + Product Details Size -+ Product Details Perfect Fit & Easy Sizing Designed for a 24" x 28" OR 28" x 24" duct opening (measured at the opening), with actual outer dimensions of 26. 5" W x 30. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 23. 75" x 27. 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