10" x 20" or 20" x 10" Cube Core Eggcrate Return Air Grille Color_Aluminum The 1/2" black insulation

The 1/2" black insulation

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+ Product Details Size - 18"w X 36"h is the size for the duct opening measurement only

4" X 14" Is The Size For The Duct Opening (floor/vent hole) Measurement Only

10" x 20" or 20" x 10" Cube Core Eggcrate Return Air Grille Color_Aluminum The 1/2" black insulation+ Product Details Size 10" x 20" or 20" x 10" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 11. 75" X 21. 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