A method comprising fingerprinting, by the at least one processor, a first copy of a database with a fingerprint. The container includes a base defining the bottom wall of the container, an opposing pair of side walls, and an opposing pair of end walls. When a pressure of the gas sealed in the discharge space is X, and a distance between a center axis of the electrodes and a surface of the metal halide is m, a following expression is satisfied: 0. The inflator includes an attaching protrusion, which protrudes in the direction intersecting the axis and secures the inflator to the vehicle together with the retainer.