AIRVISOR Air Deflector for Office Ceiling Vents 24"x 24" (Set of 1) Air Deflector for Office Ceiling Vents Increase your comfort by controlling airflow from ceiling vents Install on 1,2,3 or 4 sides to achieve desired airflow patterns Fits most manufacturers 24"x24" square office ceiling vents. For Video see http://www.airvisor.com/Assembly.html The solution HVAC Service Professionals use for their customers.