An attached device for a threaded neck of a container, including a first ring provided with a thread which allows the first ring to be screwed onto a threaded neck of the container, and a second ring that rotates as one with the first ring with the aid of at least one coupling member which is separate from at least one of the first and second rings and includes at least one zone for coupling to the at least one first, second ring from which it is separate, the coupling member including a breaking zone separate from the coupling zone and intended to break starting at a threshold rotational torque applied between the first and second rings.