Through holes 14, which passes through a side wall portion 12b of an outer reinforcement 12, is formed at a lower portion of a center pillar 1. The detector device is provided with a reed switch and with amplification means for amplifying said movement of the emergency distributor member, said amplification means comprising a lever having a magnetized free end that activates said reed switch in the event of said emergency distributor member moving. 0 alkyl group per anhydroglucose unit and which carry from 0. The distal end of the stylet is blunt-shaped.