Universal external cylindrical air filters, to be applied directly to the carburator. Each filter covers a wide range of carburetor's diameters since they comes with different rubber reductions of different sizes. Marchald filters are made in Italy, self-extinguishing, class II certified and resistant to petrols and oils. Dual-layer foam design with different porosity. The external foam has marked vertical scorings to increase the impacting area of the dust. These scorings convey the dust to the extremity of the filter, delaying the decay of performance and benefittomg the engine performance. Steel clamp included.