PVC windows – the product is very complex and require a high -tech process. They consist of a double -glazed window, frames, profiles and metal accessories. Double -glazed windows consist of glasses, sash, ventilation systems, etc. D. The glass can be different quantities. There are two glasses in a single -chamber double -glazed window, and between them space. In a two -chamber glass window there are three and two between the glass space. The advantages of such windows are that they are reliable and serve for a long time.