Abstract: A flat web-shaped blank is formed with a pair of parallel recesses, each of which defines an angle of less than 90.degree. to permit the faces of the recess to press against each other when the side sections of the blank are pivoted into a U-shape. The pressing of the lateral faces of the recess against each other serves to bias the side sections away from each other. The flat blank can be wound in a coil for storage and transportation purposes. The blank can be readily shaped into a U-shaped guide rail and inserted into the groove of an associated window frame portion. Shoulders on the outside of the side sections of the blank can snap fit into grooves in the walls of the groove of the window frame portion.

Abstract: A metal frame arrangement (20, 21), for use as or in door frames, window frames (22), window casements (23) or the like, comprising a frame made of concave metal profile. The frame comprises two pairs of mutually opposite frame portions which are angled at right angles relative to the adjacent neighboring frame portion. The frame (20, 21) is made into a coherent piece in a longitudinal continuous and sectionally angled contour, by means of local cavities in the metal profile and longitudinal deformation of locally uncovered portions of the metal profile, the deformation by means of the material of the metal profile forming angle reinforcing and angle bracing means (32', 38) just by the apex of the angle between two neighboring frame portions.

Abstract: A turnable window arrangement has a window sash to be rotated about a horizontal axis through approximately 180.degree. relative to a window frame. The window frame is provided with a separately removable air screening filter secured to the frame in a position inside the swinging path of said sash. A link arm mechanism is arranged to lock the sash in different positions between completely closed and opened venting positions.