8" X 4" Adjustable AIR Supply Diffuser - HVAC Vent Cover Sidewall or Ceiling - Grille Register - High Airflow - Black w32h32 + Product Details Size -

+ Product Details Size - 40"w X 16"h is the size for the duct opening measurement only

+ Product Details Size – 14" x 28" or 28" x 14" is the size for the duct opening measurement only

Actual Filter Size – 11 3/4"w x 19 3/4" x 1"

the gap will expand and retract to meet perfect air supply needed

8" X 4" Adjustable AIR Supply Diffuser - HVAC Vent Cover Sidewall or Ceiling - Grille Register - High Airflow - Black w32h32 + Product Details Size -+ Product Details Size 8"w X 4"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 9. 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