20 microns @ 99% Oil Filters

MADE in USA High Efficiency Efficiency is a filter's ability to capture contaminants. The more efficient a filter is, the more contaminants it will remove from oil. AMSOIL Oil Filters provide a filtering efficiency in accordance with industry standard ISO 4548-12 of 99 percent at 20 microns — one of the best ratings on the market. Some competitors also claim 99 percent efficiency, but at larger particle sizes of 30 to 40 microns.