REPLACEMENT FIRE RESISTANT AIR FILTER FOR POWERFLOWF KITfused outer and inner elements prevent dirt and grime from being lodged between layers. unlike twin air, this can be a problem with two piece designs. trapped particles can restrict airflow and if dirt works its way into your engine, a pinhead sized granule will gouge your cylinder, piston and rings. thick, flat foam, greaseless sealing ring ensures maximum contact with your airbox while acting as a breathable gasket for increased air passage coarse