Air filters trap solid particles such as mineral dust, soot, and organic pieces floating in the air, which is sucked in by the engine. The progress in filter constructing and application of modern filtration materials brings the level of contaminants filtration to the level of 99,9% for particles of even few micrometers size. Whereas the I.C engines use a great amount of air during combustion process (average amount of 10m³ of air per 1 litre of fuel), filters with high filtering efficiency must also have low flow resistance and high contaminants absorptivity. Due to such properties, it is possible to extend the period between filter replacements. Modern air filters used in the automotive industry are designed and constructed in versatile shapes and sizes and made of different, optimally selected materials. All filters consist of undismountable casings and replaceable cartridge.