Abstract: An improved non-detachable end closure has an outwardly facing dome-shaped opening flap. Non-detachable end closures, wherein the rivet for tab attachment is located in the center of the opening flap, may evidence low panel distortion under internal pressure. Forming the opening flap as an outwardly-facing dome provides increased distortion resistance and making the tab ring-shaped permits nesting of the ring in shielded location to prevent accidental opening. The arrangement of a dome within a well, which nests the ring tab, permits locating an expandable securing lug for the tab to the non-detachable dome panel within an upwardly widening space between the dome and interior of the ring tab. The structure makes the ring tab relatively inaccessible and inhibits the tendency of users who are familiar with current detachable ring pull tabs from pulling the tab off and encourages the user to push the tab inwardly.