A lid comprising: a base member comprising a central planar portion; an inner sidewall that surrounds the base member and that comprises a bottom portion configured to be in contact with a side wall of a container on which the lid is placed; an outer sidewall that surrounds the inner sidewall and that comprises at least one indentation that projects towards the inner sidewall, the indentation configured to be in contact with the side wall of the container on which the lid is placed; a topwall that connects the inner sidewall with the outer sidewall; a brim sealing channel that extends around the base member and that is defined by the inner and outer sidewalls (3,4) and the topwall; an annular planar portion that connects the bottom portion of the inner sidewall with the base member, the annular planar portion positioned below the topwall and the base member; optionally, an upper portion of the inner sidewall, proximal to the topwall, which upper portion seals against an inner side wall of a container on which the lid is placed, wherein the lower portion of the inner sidewall and the upper portion of the inner sidewall are connected to each other via an everted portion of the inner sidewall that projects away from the brim sealing channel; wherein the annular planar portion comprises at least one groove therein having a bottom portion below a plane of the remainder of the annular planar portion and below a plane of the central planar portion, characterized in that the material from which the lid is fabricated is thinner in the bottom portion of the groove than portions of the groove adjacent to the remainder of the annular planar portion. a base member comprising a central planar portion; an inner sidewall that surrounds the base member and that comprises a bottom portion configured to be in contact with a side wall of a container on which the lid is placed; an outer sidewall that surrounds the inner sidewall and that comprises at least one indentation that projects towards the inner sidewall, the indentation configured to be in contact with the side wall of the container on which the lid is placed; a topwall that connects the inner sidewall with the outer sidewall; a brim sealing channel that extends around the base member and that is defined by the inner and outer sidewalls (3,4) and the topwall; an annular planar portion that connects the bottom portion of the inner sidewall with the base member, the annular planar portion positioned below the topwall and the base member; optionally, an upper portion of the inner sidewall, proximal to the topwall, which upper portion seals against an inner side wall of a container on which the lid is placed, wherein the lower portion of the inner sidewall and the upper portion of the inner sidewall are connected to each other via an everted portion of the inner sidewall that projects away from the brim sealing channel; wherein the annular planar portion comprises at least one groove therein having a bottom portion below a plane of the remainder of the annular planar portion and below a plane of the central planar portion, characterized in that the material from which the lid is fabricated is thinner in the bottom portion of the groove than portions of the groove adjacent to the remainder of the annular planar portion.