Label for: Class 4 Flammable solids - substances liable to spontaneous combustion and substances which, in contact with water, emit flammable gases. Class 4 has 3 divisions:
Division 4.1 - flammable solids such as hexamine solid fuel tablets for camping stoves; self-reactive substances and desensitized explosives.
Division 4.2 - substances liable to spontaneous combustion under the normal conditions encountered in air transport - such as Phosphorus which burns by itself when exposed to air.
Class 4.3 - substances which in contact with water emit flammable gases. i.e. "Dangerous when wet". Examples are sodium, zinc particles etc.