14" x 8" Adjustable Blade Sidewall Ceiling Register Vent Cover Diffuser Heavy Duty Stamped Steel (Listed Size is for Duct Opening or Inside Measurement) The Listed size 12"x 4"

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

actual overall outside dimension is 18

The Listed size 20"x8" is for inside duct opening measurement

The Listed size 16"x20" is for inside duct opening measurement

14" x 8" Adjustable Blade Sidewall Ceiling Register Vent Cover Diffuser Heavy Duty Stamped Steel (Listed Size is for Duct Opening or Inside Measurement) The Listed size 12"x 4"First thing to know about size selection: take the vent cover off the wall or ceiling. Measure the duct opening where the vent can fit in. Use the measurement to determine right size to buy. This product has listed size 14w X 8h is for duct opening measurement only, actual outsize overall dimensions is 16 wide by 10 high. If your duct opening size is 14 x 8, this is the right size and will fit in well. If you measure outside or surface size, you will