18" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter white + Product Description Protect and

+ Product Description Protect and secure your thermostat with this high-quality Clear Plastic Thermostat Guard

+ Product Details Size - 26"w X 28"h is the size for the duct opening measurement only

Filter Size - 23

+ Product Details Size – 22"w X 20"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 24 5/8" width X 31 5/8" height

18" x 16" Cube Core Eggcrate Return Air Filter Grille for 1" Filter white + Product Description Protect and+ Product Details Perfect Fit & Easy Sizing Designed for a 18" x 16" OR 16" X 18" duct opening (measured at the opening), with actual outer dimensions of 20. 5" W x 18. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 17. 75" x 15. 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