The division is the second number given to a hazard class. According to Wikipedia.com, the "HAZMAT Class 2 in United States law includes all gases which are compressed and stored for transportation. Class 2 has three divisions: Flammable (also called combustible), Non-Flammable/Non-Poisonous, and Poisonous." Furthermore, it is one of the safety precautions done by the U.S. to regulate volatile and poisonous compounds.