A stopping device, comprising a stopper and a plastic cap to cover a container's neck with the stopper in the neck, the cap comprising a cover and a ring surrounding the stopper and the neck when mounted onto the neck, the ring and cover being produced as a single component connected by at least one part breakable by a force parallel to a central axis of the ring directed towards the stopper, the cover having an element resting against the stopper, the breakable part having bridges extending between an outer radial edge of the cover and an inner radial edge of the ring, and a channel in an arc of a circle defined between two adjacent bridges, the length of the cover's outer radial edge and the length of the rings inner radial edge, the channel having radial width smaller than 0.3 mm and axial height more than 0.15 mm.
