US Patent 7980403 Container closure with internal threading system

A plug-type closure for use with internally threaded containers. The container includes a container body and a neck defining an internal thread. The closure includes a cap body having an annular wall extending outwardly from the cap body, configured to shroud the neck of the container. The closure further includes a generally cylindrical plug body operatively attached to and extending outwardly from the cap body. The plug body includes a thread that engages with the corresponding internal thread of the container neck to provide a leak-resistant seal.