2. with an emergency locking mechanism
Safety belts are designed with an emergency locking mechanism.
More info:
Seat belts are a vehicle safety device designed to mimic the severity of injuries sustained by drivers and passengers in the event of an accident.
The most important part of the seat belt is the lock mechanism which is a tool that makes the belt firmly hold in the event of an accident.
The locking mechanism is activated by the movement of the vehicle or by the movement of the belt.