18" X 18" ADJUSTABLE AIR SUPPLY DIFFUSER - HVAC Vent Duct Cover Sidewall or Ceiling Color_R-4.2 Yellow + Product Details Size -

+ Product Details Size - 34"w X 18"h is the size for the duct opening measurement only

Actual Filter Size – 11 3/4"w x 31 3/4" x 1"

Actual Filter Size – 13 3/4"w x 21 3/4" x 1"

actual front end outer dimensions are approximately 30 5/8" width X 20 5/8" height

18" X 18" ADJUSTABLE AIR SUPPLY DIFFUSER - HVAC Vent Duct Cover Sidewall or Ceiling Color_R-4.2 Yellow + Product Details Size -+ Product Details Size 18"w X 18"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 19. 875" width X 20" 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