ProFilter 18-19 Honda CRF250R/17-19 Honda CRF450R Ready-To-Use Air FilterA perfectly oiled ProFilter Air Filter provides maximum airflow and increased horsepower. Ready to Use Air Filters are constructed of dual layer, reticulated foam. Reticulation is a process that opens up the foam cells, allowing for increased air flow and horsepower. The dual foam layers differ in foam pore size the innermost foam consists of a denser foam to catch fine particles of sand and powder, whereas the outermost foam is constructed of a more