Due to its geometry, ensures a better collection and channelling of the air toward the interior of the filter (through the filtering element). This creates a slight effect of overfeeding which goes up proportionally with the speed of the car, by increasing considerably the quantity of absorbed air.
    Concave and convex, single-collector and multi-collector. Depending on the number of filtering surfaces, they can be set under certain angles, according to the architecture of the engine compartment (30° -- 270°)