18" x 36" or 36" x 18" Cube Core Eggcrate Return Air Grille w26h26 + Product Details Size -

+ Product Details Size - 26"w X 16"h is the size for the duct opening measurement only

12" Diameter Is The Size For The Duct Opening Measurement Only

+ Product Details Size – 20"w X 36"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 18 5/8" width X 12 5/8" height -

actual front end outer dimensions are approximately 27 5/8" width X 26 5/8" height

18" x 36" or 36" x 18" Cube Core Eggcrate Return Air Grille w26h26 + Product Details Size -+ Product Details Size 18" x 36" or 36" x 18" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 19. 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