Abstract: A one-piece plastic can lid 1, for use with a container of the lever ring type, has a periphery 20 which contacts an annular portion of the can wall 15, so as to center the lid 1 accurately relative to the can body. A recess 25 may be provided to enable a lever to be used to pry the lid 1 off the container. The recess 25 desirably includes a membrane 27 which is pierced when a lever is first used to open the container, so that rupture of the membrane 27 makes evident any unauthorized opening of the container. The lid 1 may also include one or more fins which form a seal in conjunction with an annular part 14 of the lever ring 16 of the container.