20" X 20" Heavy Duty Floor Grille - Fixed Blades Air Grille - Brown [Outer Dimensions: 21.75 X 21.75] Fixed Blades with Damper Insulation – A thick blanket Suitable for all AC 8in diameter 12125SDCLNGBX

Insulation – A thick blanket of fiberglass insulation provides you with an R-Value of 8

+ Product Details Size - 24"w X 4"h is the size for the duct opening measurement only

Actual Filter Size – 17 3/4"w x 7 3/4" x 1"

Ideal for Walls & Ceilings: Designed for seamless installation in standard 18" X 10" duct openings

20" X 20" Heavy Duty Floor Grille Fixed Blades Air Grille Brown [Outer Dimensions: 21.75 X 21.75] Fixed Blades with Damper Insulation – A thick blanket Suitable for all AC 8in diameter 12125SDCLNGBX Insulation – A thick blanket of fiberglass insulation provides you with an R Value of 8 + Product Details Size 24"w X 4"h is the size for the duct opening measurement only