A closure for a polymeric container configured to be filled with a commodity by a hot-fill process. The closure includes an outer metallic ring and a flexible membrane. The flexible membrane is removably sealed across the ring and is configured to be drawn from an outward, pre-fill configuration to an inward, post-fill configuration in response to a vacuum created within the container during the hot-fill process. In the inward, post-fill configuration the flexible membrane is concave relate to an outer side of the closure.