18" X 12" ADJUSTABLE AIR SUPPLY DIFFUSER - HVAC Vent Duct Cover Sidewall or Ceiling w20h20 + Product Details Size -

+ Product Details Size - 20"w X 34"h is the size for the duct opening measurement only

+ Product Details Size - 30"w X 30"h X 2"d (for duct opening measurement only)

Horizontal performance assures confident use of cooling temperature differential of 30 degrees Fahrenheit and greater

Actual Filter Size – 9 3/4"w x 33 3/4" x 1"

18" X 12" ADJUSTABLE AIR SUPPLY DIFFUSER - HVAC Vent Duct Cover Sidewall or Ceiling w20h20 + 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