RV and Home Brown Stamped Steel Floor Diffuser/Register with Damper 8" X 4" (Duct Opening Size) Outside Dimension 9.6"x 5.6" • Coiled Restraining Cable with

• Coiled Restraining Cable with mounting hardware for safety

• Two Swivel Fittings allowing 360° movement for added flexibility

Duct opening – a hole that holds the duct neck to allow air to come out from HVAC system

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

If your duct opening size is 10” x 6”

RV and Home Brown Stamped Steel Floor Diffuser/Register with Damper 8" X 4" (Duct Opening Size) Outside Dimension 9.6"x 5.6" • Coiled Restraining Cable withThe Listed size 8"x 4" is for inside duct opening measurement, actual outside dimension is 9. 6"x 5. 6" 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 Brown powder coating with matte finish Individually shrink wrapped with card board pad in the back for extra protection