26" x 36" or 36" x 26" Cube Core Eggcrate Return Air Grille 12in diameter + Product Details Size –

+ Product Details Size – 20" x 20" is the size for the duct opening measurement only

+ Product Details Size - 6"w X 32"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 27 5/8" width X 34 5/8" height

Actual Filter Size – 25 3/4"w x 21 3/4" x 1"

16" Circular Round Aluminum HVAC Supply Grille Air Diffuser - With Butterfly Damper - Vent Duct Cover

26" x 36" or 36" x 26" Cube Core Eggcrate Return Air Grille 12in diameter + Product Details Size –+ Product Details Size 26" x 36" or 36" x 26" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 27. 75" X 37. 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