According to the national "General Technical Conditions for Anti-theft Security Doors" and the Ministry of Public Security's "Mechanical Anti-theft Locks" regulations, the quality of a security door's mechanical lock is judged based on three aspects: the time required to resist destructive opening; the time required to resist technical opening; and the cross-opening rate between locks of the same brand and specification. There are two common types of security door locks: Class A and Class B. Class A locks are considered合格 (qualified) if they can resist destructive opening for at least 15 minutes and technical opening for at least 1 minute.
Class B locks, on the other hand, require 30 minutes of resistance to destructive opening and at least 5 minutes of resistance to technical opening. Class B locks represent the highest protection level in the Ministry of Public Security's GA/T73 "Mechanical Anti-theft Locks" standard.
