12" x 30" or 30" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Color_Aluminum Actual Filter Size – 11

Actual Filter Size – 11 3/4"w x 23 3/4" x 1"

Actual Filter Size – 13 3/4"w x 27 3/4" x 1"

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

Width vs Height:

Design – Removable door/face for easy filter change & cleaning - uses a 1" thick filter

12" x 30" or 30" x 12" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Color_Aluminum Actual Filter Size – 11+ Product Details Perfect Fit & Easy Sizing Designed for a 12" x 30" or 30" x 12" duct opening (measured at the opening), with actual outer dimensions of 14. 5" W x 32. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 11. 75" x 29. 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