18" X 12" ADJUSTABLE AIR SUPPLY DIFFUSER - HVAC Vent Duct Cover Sidewall or Ceiling Outdoor Vent Covers + Product Details Size –

+ Product Details Size – 12"w X 12"h

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Actual Filter Size – 29 3/4"w x 5 3/4" x 1"

+ Product Details Size - The listed 4" diameter refers specifically to the size of the duct opening

18" X 12" ADJUSTABLE AIR SUPPLY DIFFUSER - HVAC Vent Duct Cover Sidewall or Ceiling Outdoor Vent Covers + Product Details Size –+ Product Details Size 18"w X 12"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 19. 875" width X 14" height. High Quality High quality steel construction, no scuff powder coat durable finish, smooth, shiny, scratch resistant, no sharp edges, 2 recessed screw holes on each side with screws included, screws same color as vent cover, easy installation. Adjustable airflow control Adjustable airflow