8" X 16" or 16" x 8" Heavy Duty Floor Grille - Fixed Blades Air Grille - Brown [Outer Dimensions: 9.75 X 17.75] Height_22in + Product Details Perfect Fit 4 X 12 Is CRFG2028 Width_14in

+ Product Details Perfect Fit & Easy Sizing - Designed for a 36" x 18" OR 18" x 36" duct opening (measured at the opening)

ensuring a refined and seamless look

Actual Filter Size – 21 3/4"w x 29 3/4" x 1"

Protection – Provides the ultimate defense against any kind of weather

+ Product Details Size - 16"w X 20"h is the size for the duct opening measurement only

8" X 16" or 16" x 8" Heavy Duty Floor Grille Fixed Blades Air Grille Brown [Outer Dimensions: 9.75 X 17.75] Height_22in + Product Details Perfect Fit 4 X 12 Is CRFG2028 Width_14in + Product Details Perfect Fit & Easy Sizing Designed for a 36" x 18" OR 18" x 36" duct opening (measured at the opening) ensuring a refined and seamless look