The DEF innovative flat roof window guarantees perfect illumination of the room under the flat roof. This product is characterized by very good thermal insulation parameters and modern design. The glazing unit is fitted using innovative method of glass bonding which ensures high durability and impeccable aesthetics. With specially designed shapes of profiles, flat roof window features up to 16% greater glazing area when compared to solutions of the competition. The window can be easily manufactured in any size in the range of 60×60 120x220cm. It allows for an easy replacement of old skylights, often in non-standard sizes which do not meet current requirements of thermal insulation. Energy-efficient glazing unit used in the DEF window makes it suitable for the passive construction. The window is opened electrically using wireless Z-Wave communication module. It is equipped with a rain sensor that automatically causes the sash to close when the first drops of rain appear. The window can be manufactured in any RAL Classic colour which allows matching the colour to individual needs of the client.