10" x 28" or 28" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 30.5"] w18h18 Its professional design and solid

Its professional design and solid construction make it the perfect solution for safeguarding your thermostat against unwanted access

These are specially sized to fit into all drop ceilings

The grille features counter-sunk screw holes that prevent paint from peeling during installation

actual front end outer dimensions are approximately 36 5/8" width X 18 5/8" height

10" x 28" or 28" x 10" Cube Core Eggcrate Return Air Filter Grille for 1" Filter - Aluminum - White [Outer Dimensions: 12.5" X 30.5"] w18h18 Its professional design and solid+ Product Details Perfect Fit & Easy Sizing Designed for a 10" x 28" or 28" x 10" duct opening (measured at the opening), with actual outer dimensions of 12. 5" W x 30. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 9. 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