After a certain time the foam is soft on the ventilation flap and the clean crumbles from this. Also, the air filter should be changed from time to time (many do not at all that there are the ever so in a window). We bought the Maintenance Kit in conjunction with the heat awning and replaced in connection with the mounting equal to both parties. The set goes with us for 2 windows. Air filter and foam gasket must be cut according to the required length. If the foam seal an additional perforation for narrow grip flap is present so that everything goes well.
