The use of mounting anchors (brackets) is to be preferred to the use of wall plugs and screws for quick mounting. The boring of a hole into a window or door and the placing into it of a wall plug or a screw deteriorates the air tightness and the thermal insulation, thus creating the so called cold thermal bridge. This is a prerequisite for the creation of condensation and for later corrosion of the reinforcing metal which, though the metal is galvanized, would weaken the structure in the course of time. The metal hardware is the basis for the stability of the door-frame and of the door leaves and guarantees reliable packing of the door since the fittings are fixed, and more specially the hinges on the door leaves.