Metal-Fab MFVSCA84W Adjustable Air Supply Diffuser Grille Register, HVAC Vent Duct Cover Sidewall or Ceiling, 8 x 4-Inch, White Carefully Shrink Wrapped With Cardboard Backing To Prevent Damage In Shipment - Screws Included Multi-Shutter Damper With Easy Handle Operator Gives You Full Control Over Airflow Direction & Amount of Airflow - Can Also Be Shut Completely 3.5 X 7.75 Is The Size For The Duct Opening Measurement Only, Actual Front End Outer Dimensions Are 9.875" Width X 6" Height - SEE BELOW IN DESCRIPTION HOW TO MEASURE A GRILLE Full 190 Degrees Control of Air Direction Vertically & Horizontally Easy Unrestricted Air Flow For Your HVAC System