IPXX, where XX is two Arabic numerals.
The first marking number indicates contact protection and foreign protection level,
The second marking number indicates waterproof protection level,
The larger the number means that its protection level is better.
First digit 5: Dust protection: It can not completely prevent dust from entering,
But it will not affect the normal operation of the instrument and reduce the safety.
Second digit 4: Water-proof: Splashing water from any direction against the shell will not cause harmful effects.