28" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w26h26 1/2" White insulation will give

1/2" White insulation will give you a good R value of 3

Equipped with a lever for easy airflow adjustment and dampening

+ Product Details Perfect Fit & Easy Sizing - Designed for a 22" x 30" OR 30" x 22" duct opening (measured at the opening)

+ Product Details Size - 6"w X 14"h is the size for the duct opening measurement only

28" x 24" Cube Core Eggcrate Return Air Filter Grille for 1" Filter w26h26 1/2" White insulation will give+ Product Details Perfect Fit & Easy Sizing Designed for a 28" x 24" OR 24" x 28" duct opening (measured at the opening), with actual outer dimensions of 30. 5" W x 26. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 27. 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