32" x 36" or 36" x 32" Cube Core Eggcrate Return Air Grille Compatible With Duct 10in Think of the diameter as

Think of the diameter as a straight line from one end to the other

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

Design – Removable door/face for easy filter change & cleaning - uses a 1" thick filter

+ Product Details Perfect Fit & Easy Sizing - Designed for a 20" x 30" OR 30" x 20" duct opening (measured at the opening)

+ Product Details Size - 30"w X 12"h X 2"d (for duct opening measurement only)

32" x 36" or 36" x 32" Cube Core Eggcrate Return Air Grille Compatible With Duct 10in Think of the diameter as+ Product Details Size 32" x 36" or 36" x 32" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 33. 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