My dryer vent is angled down (for easy cleaning), which causes it to flap in every breeze. This flange closes the gap, keeping out insects and stopping that flap-flap-flap noise. I printed mine using defaults for my printer. Then I cut a rubber gasket to fit, and attached it with JB Weld. I installed it using screws, nuts, washers and lock washers through the half-round holes.