Abstract: A device of the present invention includes a closure plug for a drink bottle. The plug is provided with an inlet and an inlet valve which is arranged therein and is embodied as a reflux valve that is closed in a rest position. The device also comprises a filling device which is provided with or can be connected to a filling head. The closure plug can be coupled to the filling head in a communicating manner. Gas can be inserted into the drink bottle by the filling device via the filling head and through the inlet valve of the closure plug. The filling head opens the inlet valve when the closure plug is coupled. The closure plug is provided with an outlet and an outlet valve that is arranged therein and is embodied as a reflux valve in the rest position.