The self-defense ring belongs to the state-controlled knives, and citizens are forbidden to carry controlled knives or guns when entering public environment. According to Article 18 of the Regulations of People's Republic of China (PRC) Municipality on the Administration of Controlled Instruments, units and individuals may hold controlled instruments with the approval of the public security department of the local municipal people's government due to the needs of production and life. Article 23 stipulates that without approval, it is strictly forbidden for any unit or individual to bring controlled devices into the restricted area determined by the public security department of the people's government at or above the county level. Article 25 stipulates that if it is really necessary to bring controlled devices into restricted areas because of official activities or production and life needs, it must be reported to the public security department of the people's government at or above the county level for approval in advance. Article 26 stipulates: (Requirements for Carrying) It is strictly forbidden to carry restricted control devices into stations, docks, airports, parks, shopping malls, theaters, exhibition halls or other public places, and to take cars, trains, ships and planes.