20" x 36" or 36" x 20" Cube Core Eggcrate Return Air Grille Powder-Coat Actual Filter Size – 21

Actual Filter Size – 21 3/4"w x 5 3/4" x 1"

+ Product Details Size - 40"w X 20"h is the size for the duct opening measurement only

+ Product Details Size - 16"w X 4"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 22 5/8" width X 30 5/8" height

actual front end outer dimensions are approximately 20 5/8" width X 36 5/8" height

20" x 36" or 36" x 20" Cube Core Eggcrate Return Air Grille Powder-Coat Actual Filter Size – 21+ 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