A cap 80 for sealing a container having a closure assembly with lug members on the container for sealing with corresponding lugs on the cap 80 has a top panel 84 and a circumferential side wall panel 82, has a top panel 84 and a circumferential side wall panel 82. The top panel 84 is positioned about a longitudinal axis 50 and extends radially outwardly therefrom. The circumferential side wall panel 82 is integral with an outer peripheral edge of the top panel 84 and has first, second, and third segments 90, 92, 94. The first segment 90 extends downwardly. The second segment 92 extends radially outwardly at a first angle to the first segment 90. The third segment 94 extends downwardly from the second segment 94 at a second angle to the second segment 92.