12"w X 4"h 2-Way-Flat Stamped Steel - Vent Cover - Grille Register - Sidewall or Ceiling - High Airflow Insulated Line Set + Product Details Size -

+ Product Details Size - 4"w X 34"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 10 5/8" width X 36 5/8" height

actual front end outer dimensions are approximately 34 5/8" width X 34 5/8" height

actual front end outer dimensions are 17" Width X 17" Height

Actual Filter Size – 31 3/4"w x 25 3/4" x 1"

12"w X 4"h 2-Way-Flat Stamped Steel - Vent Cover - Grille Register - Sidewall or Ceiling - High Airflow Insulated Line Set + Product Details Size -+ Product Details 12"w X 4"h Is The Size For The Duct Opening Measurement Only, Actual Front End Outer Dimensions Are 13. 75" Width X 5. 75" Height Multi Shutter Damper With Handle Operator Screws Included Quality Packaging Carefully Shrink Wrapped With Cardboard Backing To Prevent Damage In Shipment Carefully Shrink Wrapped With Cardboard Backing To Prevent Damage In Shipment Easy Unrestricted Air Flow For Your HVAC System + Product Description