Division 1.6 comprises extremely insensitive articles which do not have a mass explosion hazard. What is required for an item to be assigned to 1.6?

1. The articles must be submerged in water during transit
2. The articles must contain only extremely insensitive substances and demonstrate a negligible probability of accidental initiation
3. The articles must be manufactured without any chemical oxidizers
4. The articles must weigh less than 50 grams per unit