Extruded aluminium alloy body. Die-cast closing flange made of aluminium alloy. A4 Stainless steel screws. The product is subjected to galvanic anodizing treatment divided into distinct phases: mechanical satin finishing, surface degreasing, anodic oxidation and finally fixing. Subsequently the product is painted by performing a double pass in-line process, which allows you to generate a single thick protective layer which then generates barrier against atmospheric agents and UV rays. This allows to achieve corrosion resistance performance in salt spray. Pre-treatment with atmospheric pressure plasma is carried out on the surface before gluing of the diffuser on products.