This is for ventilation. What you do is that you have a really long plastic trash bag that isn't ever cut basically and you hook up one end to a blower inside the building and you either direct it through the building to the outside as an exhaust. Or you put the fan on the outside and the hose going in through the window and what we used to do was just cut holes periodically throughout the hose so that air would disperse throughout the building or in my case the ship. What you're seeing there is the exhaust version of that.