28" x 36" or 36" x 28" Cube Core Eggcrate Return Air Grille w34h34 these heavy-duty louvers are ideal

these heavy-duty louvers are ideal for use in attics

Actual Filter Size – 11 3/4"w x 21 3/4" x 1"

+ Product Details Size – 8"w X 18"h is the size for the duct opening measurement only

Equipped with a lever to adjust airflow to your preference

28" x 36" or 36" x 28" Cube Core Eggcrate Return Air Grille w34h34 these heavy-duty louvers are ideal+ Product Details Size 28" x 36" or 36" x 28" is the size for the duct opening measurement only, actual front end outer dimensions are approximately 29. 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