Why are more and more people choosing 2-step hand switch?

Now 2 steps hand switch more and more people choose, why choose 2 steps hand switch?
In fact, the 2 steps hand switch is more practical than a hand brake switch.

The 2 steps hand switch has more than the first hand switch, and the first gear is the preparatory file. Pressing the second gear is the exposure. What is the necessity of the existence of the preparatory file? People are inevitably making mistakes in doing things, especially the characteristics of X-rays. The radiation to the human body is very large. The preparatory files are harmful to the human body in order to prevent false triggering. At present, in addition to the dental X-ray machine, the first-order hand brake is used. The switch, the 2-speed hand brake switch has been widely used, and the 2 steps hand switch is more advanced, which can better meet people’s needs and has high safety. At this stage, there are many types of 2-speed hand brake switches.