8" x 8" ADJUSTABLE DIFFUSER - Vent Duct Cover - Grille Register - Sidewall or Cieling - High Airflow 8"w X 8"h Is The Size For The Duct Opening Measurement Only, Actual Front End Outer Dimensions Are 9.875" Width X 10" Height - SEE BELOW IN DESCRIPTION HOW TO MEASURE A GRILLE Multi-Shutter Damper With Easy Handle Operator Gives You Full Control Over Airflow Direction & Amount of Airflow - Can Also Be Shut Completely Full 190 Degrees Control of Air Direction Vertically & Horizontally Carefully Shrink Wrapped With Cardboard Backing To Prevent Damage In Shipment - Screws Included Easy Unrestricted Air Flow For Your HVAC System