What does the security door FM01 1021 stand for

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The security door with ventilation is very usable! Not only can it be breathable, but the most important thing is security, people from outside do not open the main lock of the anti-theft door, open the inner door, and you can see the outside clearly! The physical door can only rely on the door mirror, the general door mirror is very blurry and can't see the outside, and the elderly fireworks and children can't see it when they are low! >>>More

There is no regulation of what it represents, but what personal habits represent.

Dreams are false, empty, and the product of the abnormal work of the brain cannot be believed.

1. The marble in the marble chamber corresponding to the different depths of the pit of the A and B keys has a special structure, and there is a 1mm steel ball between the upper and lower marbles. When using the A key, the height of the lower bullet in this marble chamber plus the height of the small steel ball is just flush with the lock cylinder, so the A key can be used to twist the lock cylinder to unlock; When using B key, just can be small steel ball ejected out of the lock cylinder, that is to say, the lower bead and the lock cylinder are flush at this time, so the B key can also be twisted to unlock the lock cylinder (this principle is the same as the child and mother key system), but when the lock cylinder rotates at a certain angle, the small steel ball will be subjected to the effect of the upper spring spring, fall into the blind hole that is cleverly designed on the lock cylinder in advance (this is the difference with the child and mother key system), some people call this small blind hole a trap, very appropriate. The diameter of this blind hole is larger than the small steel ball, but smaller than the diameter of the marble, otherwise the marble will fall and the lock cylinder will be stuck and cannot be unlocked. >>>More