By definition, a material or product is fireproof if it is not subject to combustion, or combustion is delayed. The regulations attribute various fire-reaction classes according to the effects of exposure to flame.
- Class 0  applies to materials that are not subject to combustion, such as iron or steel.
- Classes 1, 2, 3, etc. refer to the flammability of the material or product.  The higher the number, the earlier the combustion, so a class 2 material starts to burn before a class 1 material.
For upholstered or stuffed products, such as mattresses, pillows and sofas, the letters “IM” (stuffed) are added to the class number, giving the complete classification Class 1 IM. Italian regulations have established Class 1 IM* is the minimum fire-resistant requirement and specific procedures for APPROVAL  of the class have been drawn up.