An independent testing carried out by University of Wales Trinity St David, Sprint Filter’s P08 polyester tissue, the “standard” tissue found in Sprint Filter replacement air filters, provided the best airflow of any leading brand air filter, including leading brand “race” filters. Sprint Filter P08 uses a special polyester filtering media with a wire diameter of only 70 microns. Its unique weave pattern can filter debris as small as 80 microns while having the highest permeability for any other air filter brand on the market (our P08F1-85 excluded). The increased airflow of the P08 air filter.