Fits 20x20 Duct Opening Stamped Steel Return Air Grille Vent Cover Grille for Sidewall and Ceiling in White Surface Dimensions: 21.75"W X 21.75"H (20" W x 20" H Duct Opening) The Listed size 12"x 4"

The Listed size 12"x 4" is for inside duct opening measurement

The Listed size 24"x14" is for inside duct opening measurement

The Listed size 8"x 4" is for inside duct opening measurement

Adjustable blade allows all horizontal direction air deflection

Fits 20x20 Duct Opening Stamped Steel Return Air Grille Vent Cover Grille for Sidewall and Ceiling in White Surface Dimensions: 21.75"W X 21.75"H (20" W x 20" H Duct Opening) The Listed size 12"x 4"The Listed size 20"x20" is for inside duct opening measurement, actual outside dimension is 21. 75"x21. 75" Stamped Face Steel Construction with 1 2" fin spacing for high air flow applications. Screws are included for easy installation White Powder coating with matte finish Individually packed with cardboard box for ultra protection