BMC Air Filter FM617-20_BMC_AIR. The materials used are the best currently available in the market. The filters are made from a single rubber frame to prevent any breakage. The filtering element is made of a special cotton fabric (4 layers) soaked in a low tack oil. It is comprised of an aluminum net treated with an epoxide solution to resist the gasoline vapors and oxidation. In addition, the cotton has the advantage of being washed out and reusable. These features guarantee a higher air flow rate from the original paper filters, minimal pressure drop of the incoming air, and therefore better engine performance. Durability: washable and reusable, no replacement needed – Wider filter surface – Maximum air permeability (4 layers of cotton) – Higher absorption and filtering – Better pressure drop ratio – Tested by international test methods. 1x BMC Air Filter. Product Type: Air Filter. You can send us a message by using the “Questions and answers” section towards the bottom of the page.