20" x 36" or 36" x 20" Cube Core Eggcrate Return Air Grille Insulated Line Set Ideal for Walls & Ceilings:

Ideal for Walls & Ceilings: Designed for seamless installation in standard 16" X 10" duct openings

actual front end outer dimensions are approximately 10 5/8" width X 14 5/8" height

We carry sizes the big box stores don't

+ Product Details Size – 34"w X 26"h is the size for the duct opening measurement only

20" x 36" or 36" x 20" Cube Core Eggcrate Return Air Grille Insulated Line Set Ideal for Walls & Ceilings:+ Product Details Size 20" x 36" or 36" x 20" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 21. 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