Abstract: Safety closure means for bottles and other like containers of sparkling wines or other liquids comprises, in combination an outer cap or capsule adapted to enclose the container neck and to be securely retained thereto, and a self-releasing plug of elastomeric material movably arranged within and retained to said cap or capsule to enable the latter and the plug to be applied together to the container and to be similarly removed therefrom thus reducing the risk of injury by a violently ejected plug.The plug comprises a tube having therein a generally transverse integral partition having a single position of equilibrium in which at least an outer annular portion thereof extends downwardly and outwardly towards the tube.The partition is also formed with a centrally located upward projection which is engaged and depressed by the top of the cap as the latter is being applied to the container neck, thereby causing said outer annular portion of the partition to exert an outward thrust on the plug tube.