12" x 10" Adjustable Blade Sidewall Ceiling Register Vent Cover Diffuser Heavy Duty Stamped Steel (Listed Size is for Duct Opening or Inside Measurement) Listed size of 6" is

Listed size of 6" is for the duct opening measurement

The Listed size 12"x 6" is for inside duct opening measurement

The outside or overall size is 2

The Listed size 10"x 4" is for inside duct opening measurement

This product has listed size 10“w X 4”h is for duct opening measurement only

12" x 10" Adjustable Blade Sidewall Ceiling Register Vent Cover Diffuser Heavy Duty Stamped Steel (Listed Size is for Duct Opening or Inside Measurement) Listed size of 6" isFirst 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 12w X 10h is for duct opening measurement only, actual outsize overall dimensions is 14 wide by 12 high. If your duct opening size is 12 x 10, this is the right size and will fit in well. If you measure outside or surface size, you