Abstract: The invention relates to a contractable closure member for sealing an open-ended container. The closure member comprises a top wall formed of a rigid material and an elastic bottom wall formed of a flexible material and having an upwardly extending continuous side wall. The side wall has a seal formed integral therewith, and this wall is securable to the top wall whereby the bottom wall is held in spaced relationship with the top wall. A retracting lever is pivotally secured in the top wall and has an engagement end and a pusher end. The pusher end is arcuately displaceable against a central portion of the bottom wall to distend the bottom wall whereby the side wall will be drawn inwardly to remove sealing pressure when positioned for sealing engagement in an open-ended container.