8" x 18" or 18" x 8" Cube Core Eggcrate Return Air Grille Insulated Line + Product Details Size -

+ Product Details Size - 4"w X 34"h is the size for the duct opening measurement only

Measure the size of the vent opening

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Design – Removable frame for easy filter change & cleaning - uses a 1" thick filter

+ Product Details Size - 14"w X 4"h is the size for the duct opening measurement only

8" x 18" or 18" x 8" Cube Core Eggcrate Return Air Grille Insulated Line + Product Details Size -+ Product Details Size 8" x 18" or 18" x 8" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 9. 75" X 19. 75". High Quality High quality, rust free aluminum construction with smooth finished edges and counter sunk screw holes (screws included); no sharp edges.. Installation Location sidewall and ceiling. Design Cubic core eggcrate design Offers highest airflow efficiency at almost 95%, reducing