Abstract: It is provided a plugging port for connecting an element to a receiving port of an article in a releasable manner. The plugging port includes a flat portion projected from a body part of the element, two thickened guiding portions, and an elongated boss structure projecting from the flat portion. The flat portion has two parallel borders of certain length and an external border perpendicular to the two parallel borders. The two thickened guiding portions are connected respectively to the two parallel borders, each guiding portion extending parallel to the respective connected border. The elongated boss structure extends parallel to the external border.