Model S985N9. Series 9 size (unthreaded drop-in style) intended for a Series 9 compatible adapter, retaining ring or shade. Lenses in the 62-85mm range are generally appropriate for Series 9 use. The Tiffen Series 9 S985N9 is a combination 3-stop neutral density filter & a 85 Color Conversion filter, for producing natural colors when shooting with tungsten film outdoors.