26" x 30" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Compatible With Duct 12in + Product Details Perfect Fit

+ Product Details Perfect Fit & Easy Sizing - Designed for a 20" x 36" OR 36" x 20" duct opening (measured at the opening)

Its locking eight-tumbler mechanism and supplied key safeguard your thermostat from tampering

Insulation density is 30kgs/cbm = 0

+ Product Details Size – 8" x 18" or 18" x 8" is the size for the duct opening measurement only

26" x 30" Cube Core Eggcrate Return Air Filter Grille for 1" Filter Compatible With Duct 12in + Product Details Perfect Fit+ Product Details Perfect Fit & Easy Sizing Designed for a 26" x 30" OR 30" x 26" duct opening (measured at the opening), with actual outer dimensions of 28. 5" W x 32. 5" H. Please check the measuring guide to ensure a proper fit. Filter Size 25. 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