Filter Factor: The 9 gears density viewing filter is a variable neutral density viewing filter with a 2x to 512x filter factor that allows you to pre visualize exposures based on lighting conditions used in film and photography. 9 Gears Adjustable: The viewing filter has a density range of 1 to 9 levels, from 0.3 to 2.7, which allows the filter to be used in situations ranging from very dim to exceptionally bright. Compressing Visual Contrast: While using this filter to preview your scene, you can also compress the visual contrast to fit the contrast of a color film or digital sensor, which has a much more limited range of contrast than the human eye. Approximate Lighting Ratios: This filter provides the ability to approximate lighting ratios and to better understand how shadows and highlights are displayed after recording. Premium Optical Glass: The filter is made of premium optical glass material, variable neutral density viewing filter, provide good using experience.