Fits 16x8 Duct Opening Stamped Steel Return Air Grille Vent Cover Grille for Sidewall and Ceiling in White Surface Dimensions: 17.75"W X 9.75"H (16" W x 8" H Duct Opening) The listed size 12" x

The listed size 12" x 10" is for the inside duct opening measurement

25” high

The Listed size 24"x10" is for inside duct opening measurement

Individually shrink wrapped with card board pad in the back for protection

If your duct opening size is 8” x 4”

Fits 16x8 Duct Opening Stamped Steel Return Air Grille Vent Cover Grille for Sidewall and Ceiling in White Surface Dimensions: 17.75"W X 9.75"H (16" W x 8" H Duct Opening) The listed size 12" xThe Listed size 16"x8" is for inside duct opening measurement, actual outside dimension is 17. 75"x9. 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