12" X 4" ADJUSTABLE AIR SUPPLY DIFFUSER - HVAC Vent Duct Cover Sidewall or Ceiling Copper Coil-Insulated Line Set + Product Details Size -

+ Product Details Size - 28"w X 28"h is the size for the duct opening measurement only

Some of the best features aren't readily apparent

Actual Filter Size – 21 3/4"w x 29 3/4" x 1"

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

12" X 4" ADJUSTABLE AIR SUPPLY DIFFUSER - HVAC Vent Duct Cover Sidewall or Ceiling Copper Coil-Insulated Line Set + Product Details Size -+ Product Details Size 12"w X 4"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 13. 875" width X 6" 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