If your window is a vertical/horizontal sliding window, insert the complimentary window seal plate in window gap, then install the exhaust pipe through the plate. If your window is a casement window, then use the complimentary air vent flap: Prepare an acrylic board or wooden board (purchased separately) and cut out a circle which fits the outer circumference of the air vent flap. Fit the air vent flap into the hole then seal the window with the board. Lastly insert the pipe into the air vent flap. When the unit is not in use or moved to another room, the air vent flap can be closed to shut out heat and dust.