Aisi 409 stainless steel is particularly resistant to corrosion, as well as to high temperatures, climatic and chemical agents and soil acidity. This type of stainless steel has a chromium content ranging from 11% to 30%. The chromium, oxidizing in contact with oxygen, is transformed into chromium oxide which prevents the pole from further oxidation. This process, called "passivation", allows the pole, which has scratches or abrasions of any kind, to spontaneously regenerate the oxide patina that protects its surface.