Class windows are not in vain. That is, Both The Profile, and Glass, and Accessories Used in the Production of these Windows Do Differ in Goodo Quality. Their Double -glazed Windows Are Made of M1 Brand Glasses that A Standard Version of Glasses Used for Thefacture of Double -glazed Windows. In Principle, in Spite of the Cheapness of the Windows of this Class, They Canast of Quite Toleble Characteristics.