Molded lid with wave configured central portion

摘要

A molded lid having an intermediate region configured as a sequence of waves, each of curved cross-section forming successively occurring crests and troughs, and exhibiting amplitudes increasing in value from the lid center toward the rim. The waves terminate at a ring band which is located to slide in adjacency with the inwardly disposed side of a plastic drum. The lid is provided with a polymeric gasket which is retained in position by a retainer band which is insertable in sliding compressive engagement within a retainer cavity.