20" X 20" ADJUSTABLE AIR SUPPLY DIFFUSER - HVAC Vent Duct Cover Sidewall or Ceiling 8" Diameter Actual Filter Size – 13

Actual Filter Size – 13 3/4"w x 29 3/4" x 1"

+ Product Details Size – 20"w X 24"h is the size for the duct opening measurement only

And The Cooler Air From Outside WIll Flow In From The Bottom

Heavy-gauge all-steel construction

20" X 20" ADJUSTABLE AIR SUPPLY DIFFUSER - HVAC Vent Duct Cover Sidewall or Ceiling 8" Diameter Actual Filter Size – 13+ Product Details Size 20"w X 20"h is the size for the duct opening measurement only, actual front end outer dimensions are approximately 21. 875" width X 22" 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