RV and Home White Stamped Steel Floor Diffuser/Register with Damper 10" X 4" (Duct Opening Size) Outside Dimension 11.5"x 5.5" Listed size of 8" is

Listed size of 8" is for the duct opening measurement

If your duct opening size is 10” x 8”

Neck Size 8”

actual outsize overall dimensions is 16“ wide by 10” high

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

RV and Home White Stamped Steel Floor Diffuser/Register with Damper 10" X 4" (Duct Opening Size) Outside Dimension 11.5"x 5.5" Listed size of 8" isVersatile: 10x4 inch floor vent suitable for RVs and other applications. Durable Construction: Made from high quality materials for long lasting performance. Easy Installation: Designed for straightforward installation in various floor surfaces. Efficient Airflow: Allows proper ventilation and air circulation. Space Saving: Compact size maximizes usable floor space.