Re-usable, long-life Challenger air filters are designed to give up to a 50% increase in airflow performance over other filter brands. This typically translates into a 2-4% increase in horsepower as well as increased fuel economy. Installation requires no modifications (they are direct filter replacements). Filters require cleaning & oiling every 100 hours; cleaning operations may be repeated up to 25 times before filters must be replaced. FAA-PMA approved. CPE1957 requires 990704 Sealing Grease for installation.