Abstract: A plastic container lid is formed by injection molding and comprises a sheet-like main body portion with a downwardly-open hollow upwardly-extending annular projection extending around the periphery of the body portion, the annular projection having an inner wall extending upwardly from the periphery of the body portion, a top wall extending radially outwardly from the top of the inner wall and an outer wall extending downwardly from the outer periphery of the top wall, with the inner and outer walls being substantially equal in height. An annular skirt portion which extends outwardly from the lower end of the outer wall and curves to extend downwardly to a lower annular edge. The skirt portion has an internal annular rib extending around and projecting inwardly from the inner surface of the skirt portion.