Description Fleetguard AF899NF is a NanoForce primary axial seal air filter with nanofiber media rated 99.99% efficient per ISO 5011 for fine dust control. Suitable for off-highway mining and construction equipment and other heavy-duty applications using OEM filters such as Caterpillar 1W3637 and 1327172, Cummins A034R957, Perkins CH11396, Liebherr 5610969, Komatsu VJ5175 and equivalent part numbers.