Convair coolers work by a process of evaporation and do not use environmentally harmful CFC gases. Just as in nature, where air is cooled by passing over the sea, the air going through a Convair unit is also cooled by passing over water. Air is drawn through a large wet filter pad by a powerful fan and is cooled by the process of natural evaporation. The units are most effective in a draft environment i.e. the back of the unit must face an open window and must blow cool air towards an open door or window. All units have high-tech polymer construction for a long corrosion-free life. Twin castor wheels make it easy to move the cooler from room to room.