Door locks are widely used and can be seen every day, but there are many levels of anti-theft door locks, that is, anti-theft level. The following is a comparison table of anti-theft technical indicators of anti-theft door locks. According to this comparison table, we can understand the safety performance of our own door-level locks.

Sometimes, due to the gravity of the door leaf or the door hinge, the door leaf sinks, and the door is locked or not opened smoothly. At this time, it is very difficult to open and lock the door with the key. At this time, do not twist the key forcibly, so as not to break the key and increase trouble.
 

The correct solution: you should check the reason first. If the door leaf is sinking due to loose leaf, fix the loose leaf with screws. If the door frame is deformed or the reason is irreversible, you can start with the door frame and expand the bolt accordingly, so that the door lock can open and close the door smoothly.