The plastics stopper consists of a hollow cylinder closed at its base. The upper section of the stopper is of increased thickness, while the middle section presses against the inner diameter of the neck of the bottle to seal it. The lower section of the stopper is narrower than the upper sections but has downward-projecting ridges which support the clamping action of the stopper while the stopper is being inserted by a machine. The base part which closes the hollow cylinder is not at the very bottom of the stopper but within the centre section which presses against the bottle neck and is slightly cambered downwards. The downward-projecting ridges are located beneath the centre-section stopper base. The centre and lower sections of the stopper are slightly conical. The outer centre section of the stopper may have transverse ridges.
