Abstract: A sheet metal part for use in housing for accommodating devices such as electrical, electronic and optical devices is described. The sheet metal part comprises a penetrable opening through which the shank of a screw may be provided to bring the penetrable opening from an unpenetrated state to a penetrated state. The penetrable opening in the unpenetrated state is covered by an airtight coating layer, has a central area configured to accommodate a threaded shank of the screw and a lug extending radially outward from the central area over some distance, and the lug of the penetrable opening is configured to be bent back with the central area without coming loose from the sheet metal part when the penetrable opening is brought in the penetrated state by the shank of the screw.