RV and Home White Stamped Steel Floor Diffuser/Register with Damper 12" X 2" (Duct Opening Size) Outside Dimension 13.5"x 3.75" actual overall outside dimension is

actual overall outside dimension is 18

If the hole is 25" wide by 16" tall

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

Whether you prefer to leave it fully open for optimal airflow or close it off completely to redirect extra heat or air conditioning to other rooms

The Listed size 12"x12" is for inside duct opening measurement

RV and Home White Stamped Steel Floor Diffuser/Register with Damper 12" X 2" (Duct Opening Size) Outside Dimension 13.5"x 3.75" actual overall outside dimension isThe Listed size 12"x 2" is for inside duct opening measurement, actual outside dimension is 13. 5"x 3. 75" Butterfly damper with easy foot operated control dial for desired air flow Two sunk screw holes located at both sides of the register for ceiling and wall mounting with included screws. Distance between the two screw holes is 13. 25". White powder coating with matte finish Individually shrink wrapped with card board pad in the back for extra