Abstract: A plastic closure with a U-shaped rim surrounding a closure portion, an upper wall of the rim extending both upwardly and downwardly from the closure portion and flaring outwardly away from the closure portion. The upper end of the inner wall joins into the base of the `U` shape and the lower end is resiliently flexible. When fitted to a container, upper and lower ends of the inner wall seal against the lip and inner surface of the wall of the container, resiliency of the inner wall of the closure ensuring its sealing engagement with the container wall.