Abstract: A shield structure for limiting transmission of electromagnetic radiation between two locations, one of which is inside the shield structure and the other of which is outside the shield structure, comprises first and second shell portions of electrically-conductive material. The first shell portion has a rim that defines an opening. A major part of the second shell portion corresponds substantially in shape to the shape of the opening, and its size is slightly smaller than that of the opening. One of the shell portions has tabs that are distributed about the opening and project towards the other shell portion. The tabs are electrically conductive, and provide electrically-conductive contact between the first and second shell portions.