Sierra International Marine Universal 21 Micron Replacement Filter removes over 98.8 percent of emulsified water from your gasoline. Sierra"s 10 micron filters are over 90 percent efficient at removing particles as small as 10 microns. All filters flow at 90 GPH to feed even the hungriest motor. Sierra 10 micron filters are recommended to prevent damage to sensitive inboard and outboard fuel injection systems.