0: no protection

1: Water droplets into the shell have no effect

2: When the shell is tilted to 15 degrees, the water droplets into the shell have no effect

3: Water or rain has no effect from the 60 degree corner to the shell

4: The liquid splashed into the shell from any direction has no harmful effect

5: Rinse with water without any harm

6: Can be used in the cabin environment

7: Can withstand water immersion in a short time (1m)

8: Long-term immersion in water under certain pressure