Container closures

A closure member for an open-ended container comprising a resilient bottom closure member in which the outer edge thereof constitutes sealing means sealable against the inside wall of said container, and a top closure member interconnected with said resilient bottom closure member, said top closure member including a central pivotally mounted rocker or toggle adapted to operate a downwardly extending cam member and said bottom closure member including a central upwardly extending buttress member adapted to cooperate with said cam member to impart an alternating movement in said closure member from either a sealing position or an unsealed position, wherein in one position of said pivotally mounted rocker said sealing means of said resilient bottom closure member remain in sealable contact with the inside walls of said container and wherein in a second position of the pivotally mounted rocker said cam member acts on said buttress member to cause a downward movement of the buttress and to substantially uniformly displace said sealing means such that said closure member can be readily positioned in or removed from the open-ended container.