Twin Air 150607P Foam Air Filter for Honda CRF1000L 16-19This is where it all began. Over 50 years ago, the sandy, gritty soil of The Netherlands and the resulting engine failures proved that single foam and paper filters gave riders air flow, but failed at protection. Twin Airs breakthrough, fused dual layer design (now widely copied) combined performance and protection. The fused layers of open pore foam and fine inner foam trap even the smallest particles. The new, rounder design boosts airflow. So do