Abstract: A closure device for providing a seal with a container having a shallow external bead in the region of the mouth-defining rim of the container. The closure device comprises a central panel and a skirt joined by a sector forming an internal channel containing a molded plastic gasket. A portion of the gasket extending along an internal surface of the skirt is provided with a number of projections each having a shallow, rectangular, prismatic configuration. A lower portion of each projection is adapted to extend beyond the container bead to retain the closure device on the container.