The Formatt-Hitech 6.6 x 6.6" Soft Edge Graduated Neutral Density 0.3 Glass Filter helps to specifically darken skies and other bright areas of the image. The filter is densest at the edge and fades to clear in the middle, with a soft edge transition line between the density and clear areas. By only having a portion of neutral density on the filter, you can selectively darken areas of an image whilst allowing the portion of the image in the clear section to receive normal exposure. Neutral density filters do not affect the colouration of the image and the 0.3 density provides a one-stop reduction of light entering the lens.nnFormatt-Hitech Glass filters are made from high-quality Schott Superwite glass for exceptional clarity and maintained light transmission. This filter measures 6.6 x 6.6" / 167.6 x 167.6 mm.nnn- 0.3 Soft Edge Graduated ND filter to darken skies and other bright areas of the image.nn- Provides a one-stop light reduction in selective areas.nn- The soft edge transition is ideal for situations where there is no distinct separation line between bright and dark areas of the image.nn- Neutral density filters do not affect the overall colouration of the image.