Abstract: A stopper for a pressure container comprises a hole fitting and an inner core for sealing engagementin a generallycylindrical inner bore of the hole fitting. The hole fitting has an annular external groove for receiving a generally circular edge of the container which edge defines an opening in the container. The part of the hole fitting immediately below the groove is of larger external diameter than the opening in the container, and the core has a non-sealing section of less external diameter than the internal diameter of the adjacent length of the bore. Such a stopper is easier to insert in the container opening.