36" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Grilles Design – This airflow control

Design – This airflow control component are made to connect to a drop ceiling lay-in diffuser grille

+ Product Details Size – 18"w X 12"h is the size for the duct opening measurement only

Installation Location – Sidewall or ceiling

actual front end outer dimensions are approximately 36 5/8" width X 34 5/8" height

+ Product Details Size - 25"w X 12"h is the size for the duct opening measurement only

36" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Grilles Design – This airflow control+ Product Details Perfect Fit & Easy Sizing Designed for a 36" x 24" OR 24" x 36" duct opening (measured at the opening), with actual outer dimensions of 38. 5" W x 26. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 35. 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