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 at least a portion of the side wall will be drawn inwardly to remove sealing pressure when positioned for sealing engagement in an open-ended container.