Which maintain a low temperature inside the filter and consequently generate a thermal equilibrium between the surface of the walls of the filter and the absorbed air. As a result, the temperature of the air is significantly decreased before it leaves the air filter (phenomenon known as pre-cooling of the absorbed air). The filters can be equipped with A.D.T.S. in order to maintain an optimal temperature of the absorbed air, related to the temperature of the engine compartment. They also fulfill multiple tasks, in addition to the main air filtering function, such as enhancing the degree of absorption and collection, increasing the speed of the absorbed air