34" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Aluminum - Cube Core and with a built-in back

and with a built-in back 1/2" mesh they also protect you from annoying rodents like mice

actual front end outer dimensions are approximately 34 5/8" width X 30 5/8" height

and then smoothly drop in the grill

Durable stamped steel construction ensures long-lasting performance

34" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Aluminum - Cube Core and with a built-in back+ Product Details Perfect Fit & Easy Sizing Designed for a 34" x 24" Or 24" x 34" duct opening (measured at the opening), with actual outer dimensions of 36. 5" W x 26. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 33. 75" x 23. 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