Abstract: An efficient one-piece cap-style closure device is hereby provided for re-covering a partially emptied cardboard frozen food container. The device is so obvious to operate, that no instruction is needed for immediate usage. The key functional element is the bonded inner lining of resilient material. When pressed down over the open end of the cardboard container, the lining forms a moderately tight fitting seal between the cap and the outer surface of the container. This permits handling and re-storing of the partially emptied container without mishap.