This is an adapter flange for fitting the standard 5 inch exhaust tubes for in room air conditioners between different ac units. To use, remove the connector from the back of a unit and fit this flange over the exposed tube. Then the flat parts of the flange can be duct taped to the exhaust port of an ac unit that the tube does not normally connect to. I used this to get an old unit working again after its exhaust tube had been lost. Print at high infill. It will likely warp due to heat after being used, especially if made from PLA.