The electronically operated DEF DU6 window is suitable for illuminating and ventilating rooms under flat roofs. It offers excellent thermal-insulation parameters, is equipped with a chain drive that is concealed inside the frame and can be integrated with modern home automation systems. Its contemporary design manages without any plastic domes. A special feature is the triple or quadruple glazing and the topmost pane which is markedly bigger than the subsequent panes, so that the entire unit allows for virtually frameless fitting into the casement.