The class number is just a designation set by the American Society for Testing and Materials. They're the folks that write the testing specs for insulating gloves.
Class 00 just designates that the gloves can be used up through 500 volts.
Other classes are:
Class 0 = 1000V
Class 1 = 7500V
Class 2 = 17,000V
Class 3 = 26,500V
Class 4 = 36,0000V
-John
