CLASS 1_ Explosives: for the first three subcategories, their label includes an exploding bomb and the number 1 at the bottom. In the last three categories, the number of each type is added (1.4;1.5;1.6) and the number 1 at the bottom.   CLASS 2_Gases: 2.1 Flammable gases when in contact with heat: it is identified with the symbol of a flame (black or white) on red. 2.2 Flammable and non-toxic gases: it consists of a black or white cylinder on the green. 2.3 Toxic gases by inhalation: a black skull appears on a white background.   CLASS 3_Flammable liquids: it bears the flame symbol and the number 3 in the lower corner.   CLASS 4_Flammable solids: 4.1 Flammable solids under normal conditions: their label has a black flame on a background of vertical red and white stripes. 4.2 Substances that can undergo spontaneous heating and inflammation: their symbols are divided into a white background at the top and a red background at the bottom. There is also a black flame on white. 4.3 Substances that can ignite when they come into contact with water: it differs from the previous pictograms in that the background is blue.   CLASS 5_Comburent and organic peroxides: 5.1 Oxidizing substances: a flame in a circle appears on its label, with a yellow background and the number 5.1 at the bottom. 5.2 Organic peroxides: their signal is a white or black flame on a background that is half red and half yellow. The number 5.2 also appears.   CLASS 6_Toxic and infectious: 6.1 Toxic substances: in its symbology appears a black skull on a white background and the number 6. 6.2 Infectious substances: the symbol of the three superimposed moons appears on a black circle and a white background   CLASS 7_Radioactive: It is divided into three categories that contain the radioactive trefoil symbol and data regarding the content, quantity and activity to which they are dedicated. Categories II and III have the upper half with a yellow background and show greater danger.   CLASS 8_Corrosive: they are identified because two test tubes appear, one pouring its content on a surface and the other on a hand. The bottom is black and the number 8 is also included.   CLASS 9_They present various dangers: their label is divided into two halves, in the upper part there are vertical black and white stripes and in the lower part the number 9 appears.