Abstract: Disclosed herein is a plastic frame for leading lines through an opening in a structural part, such as a wall. The frame has a cavity defined by two C-shaped elements having inner flanges which are perpendicular to the plane of the frame, and outer flanges which are parallel to the plane of the frame. The leg portions of one of the C-shaped elements extend toward the leg portions of the other. A double T-shaped element can be situated between the C-shaped elements in order to form two cavities. The frame is useful for obtaining a water-tight and/or gas-tight seal when wires, tubes, etc. are led through a wall.