Abstract: A snap-on lid for covering opened beverage cans securely enough to contain effervescent gases effectively during storage of the beverages in such a container, including a collar defining a groove which is downwardly open to receive an upwardly-directed edge of the container. A convex dome is located within the area circumscribed by the collar, and a flexible annular portion surrounds the dome portion of the lid and interconnects it with the collar. A skirt depends from the outer side of the collar portion and fits sealingly against the outer surfaces of the container. An upper margin of the skirt has an inner diameter smaller than that of the outer wall of the collar, presenting an inwardly-directed lip along the open edge of the groove defined by the collar, to engage the bottom of a bead defined at the top of the container and thus aid in retaining the lid in place on the container.