The Tiffen 4 x 4" 85/0.9 ND combination filter combines an 85 amber colour conversion filter and a 0.9 neutral density filter., , The ND filtration provides a 3-stop exposure reduction to darken the entire image, allowing you to photograph with a wider aperture or slower shutter speed than normally required. The 85 filtration covers the entire filter plane and converts the colour temperature to 3400K for use with Type A (tungsten) films., , This filter is constructed from water white glass and manufactured using ColorCore technology, a process involving laminating the filter substrate between 2 pieces of optical glass, and polishing it flat to a tolerance of 1/10,000th of an inch. This filter measures 4 x 4" / 101.6 x 101.6 mm., , -Combination of an 85 amber colour conversion filter and a neutral density filter., -The 0.9 ND filter darkens the image, allowing you to photograph with a slower shutter speed or wider aperture than normally required., -The 85 filter converts the colour temperature to 3400K, enabling you to use Type A tungsten-balanced films in daylight situations., -Water white optical glass for excellent clarity.