The sales manager of plastic windows must be able to convey all these circumstances to the customer and be able to represent the advantages of his company against the backdrop of a rampant of low professionalism in the industry in a profitable light. After all, the basic laws of marketing indicate that for a successful sale it is necessary to identify the needs of the client and show the path of their implementation. And the need of the customer of the windows is his quality. And the quality of the installation is a huge problem of the window industry. This is especially true for mass plastic windows, because in the manufacture of elite (historical, Finnish, Scandinavian, English) wooden structures, the installation quality is usually observed to a much greater extent.