Sierra fuel water separators remove over 99.8% of emulsified water from your gasoline. Sierra's 10 micron filters are over 90% efficient at removing particles as small as 10 micron. All filters flow @ 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. Outdrive drain and vent screw gasket.