US Patent 6942116 Container base structure responsive to vacuum related forces

A plastic container having a base portion adapted for vacuum pressure absorption. The base portion including a contact ring upon which the container is supported, an upstanding wall and a central portion. The upstanding wall being adjacent to and generally circumscribing the contact ring. The central portion being defined in at least part by a central pushup and an inversion ring which generally circumscribes the central pushup. The central pushup and the inversion ring being moveable to accommodate vacuum forces generated within the container.