12" Round Ceiling Diffuser White Powder Coated with Outside Dimension of 16" Fitting in 12" DuctFirst 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 12'' X 12'' is for duct opening measurement only, actual outsize overall dimensions is 16'' X 16''. If your duct opening size is 12, this is the right size and will fit in well. If you measure outside or surface size, you will get a

high resistance to abrasion and chemical

Sidewall/Ceiling Register Measurement

If your duct opening size is 14” x 6”

Individually shrink wrapped and packed with card board box for extra protection

it refers to the size of the "tongue"  so that it will fit in a 8"x8" hole

actual outsize overall dimensions is 16'' X 16''

actual outsize overall dimensions is 8“ wide by 8” high

For use in low pressure applications

reliable performance that enhances your home

This tubing can withstand multiple uses

18" long heavy duty steel construction with oil brushed powder coating finish

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